MEDICAL  BOOKSELLERS, 
No.  1012   Walnut   Street, 

PHILADELPHIA. 


THE  LIBRARY 

OF 

THE  UNIVERSITY 
OF  CALIFORNIA 

PRESENTED  BY 

PROF.  CHARLES  A.  KOFOID  AND 
MRS.  PRUDENCE  W.  KOFOID 


Entered  according  to  the  Act  of  Congress  in  the  year  1898,  by 

LEA   BROTHERS   &   CO., 
In  the  Office  of  the  Librarian  of  Congress.     All  rights  reserved. 


DORNAN,    PRINTER. 


wir 


TO  THE 

MEMORY  OF  MY  FATHER, 

TO   WHOM  I   OWE   SO   MUCH  J   TO  WHOM  I   CAN    REPAY  SO   LITTLE, 

THIS  VOLUME 

IS    MOST    AFFECTIONATELY 

DEDICATED. 


PREFACE. 


•FoR  a  number  of  years  past  it  has  seemed  to  the  author 
that  there  was  need  for  a  manual  or  text-book  which  would 
give  a  plain  statement  of  the  fundamental  principles  and  facts 
of  Hygiene  and  Sanitation,  together  with  such  explanations 
and  details,  based  on  American  practice,  as  would  serve  to 
make  the  work  clear  and  readable. 

Of  all  the  medical  sciences  that  is  clearly  the  most  impor- 
tant which  prevents  disease  instead  of  curing  it,  and  deals  with 
communities  as  well  as  with  individuals.  The  vital  inter- 
est and  comparative  simplicity  of  this  science  have  already 
attracted  the  laity  in  great  numbers,  as  well  as  the  medical 
profession,  and  to  this  intelligent  interest  are  largely  due  the 
remarkable  advances  which  recent  years  have  witnessed  in 
methods  of  preserving  the  public  health. 

The  desultory  and  often  unauthoritative  articles  in  the 
daily  press  or  monthly  magazines  are  scarcely  fit  material 
for  satisfying  this  desire  for  knowledge,  nor,  on  the  other  hand, 
can  we  expect  any  extensive  study  of  the  larger  volumes  on 
the  subject.  Smaller  works  exist,  but  they  are  either  diffuse 
and  lacking  in  system,  or  they  detail  methods  and  devices 
adopted  abroad  and  out  of  harmony  with  conditions  here.  It 
is  important  for  the  medical  student,  at  least,  that  the  in- 
formation given  in  such  a  text-book  as  the  present  should  be 
as  concise  and  systematic  as  possible,  and  that  it  should 
devote  special  attention  to  those  conditions  with  which  he  is 
practically  concerned. 

For  these  reasons,  and  because  I  have  as  yet  found  nothing 
which  exactly  comprises  my  idea,  I  have  ventured  to  offer 
this  volume  not  only  to  my  classes,  but  to  all  who  are  desirous 


vi  PREFACE. 

of  doing  what  they  can  to  better  the  health  of  themselves  and 
of  those  about  them.  The  volume  deals  with  personal  as 
well  as  public  health. 

In  the  preparation  of  the  work  the  principal  text-books 
have  been  fully  consulted,  as  well  as  such  recent  magazine 
and  other  articles  of  authority  as  were  pertinent.  Quota- 
tions have  been  credited  and  references  indicated,  in  order 
that  the  reader  may  know  where  to  seek  for  further  details  or 
fuller  information  than  the  limitations  of  this  work  will  per- 
mit. Indeed,  I  should  do  wrong  were  I  to  give  any  one  the 
idea  that  this  volume  is  thoroughly  comprehensive,  or  even  a 
compendium  of  the  whole  scope  of  hygiene  or  intended  to  be 
so.  The  science  is  already  too  great  and  too  important  to 
be  treated  entirely  in  a  single  volume,  and,  as  it  is  so  inti- 
mately concerned  with  every  one's  personal  welfare,  it  is  the 
author's  earnest  hope  and  desire  that  not  only  his  students 
but  others  may  use  this  as  an  adjunct  to  further  and  more 
extensive  reading,  and  that,  inasmuch  as  hygiene  is  destined 
to  be  even  more  important  in  the  future  than  it  is  now,  all 
should  make  use  of  all  possible  sources  of  authoritative  in- 
formation. 

Whatsoever  may  be  the  faults  or  shortcomings  of  the  work, 
the  labor  expended  upon  it  will  not  have  been  altogether  in 
vain  if  it  induces  any  one  to  take  greater  interest  in  the  study 
of  all  that  which  pertains  to  ' '  the  preservation  and  promotion 
of  health  and  the  prevention  of  disease." 

The  illustrations  have  been  selected  with  special  reference 
to  the  text,  and  those  of  special  devices  or  apparatus  have 
been  chosen  as  trustworthy  representatives  of  their  respective 
classes.  For  the  four  photo- micrographs  of  bacteria  I  am 
indebted  to  the  skill  and  courtesy  of  Dr.  William  Gray,  of 
Washington,  D.  G.,  to  whom,  and  to  all  my  other  friends  and 
associates  who  have  aided  me  in  the  preparation  of  the  work, 
I  have  many  thanks  to  extend. 

SENECA  EGBERT. 

PHILADELPHIA,  MAY,  1898. 


CONTENTS 


CHAPTER  I. 
INTRODUCTION .17 

CHAPTER  II. 
BACTERIOLOGY 32 

CHAPTER  III. 
THE  ATMOSPHERE— AIR 59 

CHAPTER  IV. 

VENTILATION  AND  HEATING        .        .        .        ...      88 

CHAPTER  V. 
WATER .    126 

CHAPTER  VI. 
FOOD .        .        .    180 

CHAPTER  VII. 
STIMULANTS  AND  BEVERAGES       .        .        .        ....    220 

CHAPTER  VIII. 
PERSONAL  HYGIENE 228 

CHAPTER  IX. 
SCHOOL  HYGIENE  .  253 


viii  CONTENTS. 

PAGE 

CHAPTER  X. 
DISINFECTION  AND  QUARANTINE 266 

CHAPTER  XI. 

THE  REMOVAL  AND  DISPOSAL  OF  SEWAGE  .        .        .        .298 

CHAPTER  XII. 
VITAL  STATISTICS 327 

CHAPTER  XIII. 
THE  EXAMINATION  OF  AIR,  WATER,  AND  FOOD  .        .        .    339 


A  MANUAL  OF  HYGIENE  AND  SANITATION. 


CHAPTER    I. 

INTRODUCTION. 

HYGIENE  may  be  defined  as  the  art  and  science  that 
considers  the  preservation,  promotion,  and  improvement  of 
health  and  the  prevention  of  disease.  It  treats  of  the 
laws  of  health  in  the  broadest  sense,  and  under  the  gen- 
eral term  may  be  included  a  number  of  subdivisions.  For 
instance,  Sanitation  or  Sanitary  Science  is  usually  taken 
to  be  concerned  with  matters  pertaining  to  the  general 
public  health,  while  Personal  or  Domestic  Hygiene  is 
more  closely  related  to  the  affairs  of  the  individual  or 
household. 

A  little  thought  will  show  that  under  the  general  head 
we  may  consider  :  1 .  The  preservation  and  promotion  of 
health.  2.  Practical  disinfection  and  the  means  of  avoid- 
ing preventable  diseases.  3.  Adaptation  of  diet  to  the 
prevention  and  cure  of  perversions  of  nutrition;  and  that 
under  one  or  another  of  these  headings  will  fall  the  dis- 
cussion of  the  air  we  breathe,  the  water  we  drink,  the  food 
we  eat,  the  soils  and  surroundings  of  our  dwellings  and 
communities;  and  at  the  same  time,  the  study  of  the  means 
of  recognizing,  avoiding,  correcting,  or  removing  all  im- 
purities affecting  any  of  these.  In  addition,  there  must 

2 


18       A  MANUAL  OF  HYGIENE  AND  SANITATION. 

be  the  study  of  climate  and  meteorology;  of  clothing  and 
shelter;  of  the  care  of  the  sick,  that  they  may  not  endanger 
the  well;  the  dangers  of  the  abuse  of  stimulants,  narcotics, 
etc. ;  the  desirability  of  chaste  and  temperate  living,  exer- 
cise, rest,  etc. 

Parkes  says  that,  "  taking  the  word  '  hygiene'  in  its 
largest  sense,  it  signifies  rules  for  the  perfect  culture  of 
mind  and  body.  It  is  impossible  to  dissociate  the  two. 
The  body  is  affected  by  every  mental  or  moral  action;  the 
mind  is  profoundly  influenced  by  bodily  conditions.  [So 
is  the  moral  conduct  of  individuals  or  communities.]  For 
a  perfect  system  of  hygiene  we  must  train  the  body,  the 
intellect,  and  the  moral  faculties  in  a  perfect  and  balanced 
order. "  Again,  he  says  :  (<  Looking  only  to  the  part  of 
hygiene  which  concerns  the  physician,  a  perfect  system  of 
rules  of  health  would  be  best  arranged  in  an  orderly  series 
of  this  kind.  The  rules  would  commence  with  the  regu- 
lation of  the  mother's  health  while  bearing  her  child,  so 
that  the  growth  of  the  new  being  would  be  as  perfect  as 
possible.  Then,  after  birth,  the  rules  (different  for  each 
sex  at  certain  times)  would  embrace  three  epochs:  of 
growth  (including  infancy  and  youth);  of  maturity,  when 
for  many  years  the  body  remains  apparently  stationary; 
of  decay,  when,  without  actual  disease,  though  doubtless 
in  consequence  of  some  chemical  changes,  molecular  feeble- 
ness commences  in  some  part  or  other,  forerunning  general 
decay  and  death.  In  these  several  epochs  of  his  life  the 
human  being  would  have  to  be  considered :  First,  in  rela- 
tion to  the  natural  conditions  which  "surround  him,  and 
which  are  essential  for  life,  such  as  the  air  he  breathes,  the 
water  he  drinks,  etc.;  in  fact,  in  relation  to  nature  at 
large.  Second,  in  his  social  and  corporate  relations,  as  a 
member  of  a  community  with  certain  customs,  trades,  etc. ; 


INTR  OD  UCTION.  1 9 

subjected  to  social  and  political  influences,  sexual  relations, 
etc.  Third,  in  his  capacity  as  an  independent  being,  having 
within  himself  sources  of  action,  in  thoughts,  feelings, 
desires,  personal  habits,  all  of  which  affect  health,  and 
which  require  self-regulation  and  control.  Even  now, 
incomplete  as  hygiene  is,  such  a  work  would,  if  followed, 
almost  change  the  face  of  the  world/' 

The  student  will  readily  see  that  the  scope  of  the  science 
is  so  vast  that,  in  a  limited  work  like  the  present  one,  it 
would  be  impossible  to  go  over  the  entire  ground  com- 
pletely and  thoroughly.  The  most  that  can  be  attempted 
will  be  to  discuss  its  fundamental  laws  as  we  now  under- 
stand them,  especially  those  that  are  most  closely  con- 
nected with  the  conscientious  physician's  duties  and  prac- 
tice, and  to  show  the  reason  of  or  the  advantages  resulting 
from  the  pursuit  of  hygienic  and  sanitary  methods  based 
on  those  laws  and  our  experience.  Hygiene  is,  however, 
a  science,  in  the  study  of  which  common  sense  must  be 
freely  used,  and  if  one  but  bring  this  to  his  aid  and  add 
to  it  sincere  attention,  he  will  speedily  find  that  there  is 
little  that  is  difficult,  beyond  his  grasp,  or  less  than  really 
fascinating. 

It  always  has  been,  as  it  always  will  be,  an  art  to  pre- 
serve health  and  to  ward  off  disease.  Hippocrates,  about 
400  B.  C.,  in  his  treatise  on  Airs,  Waters,  and  Places, 
was  the  first  to  define  principles  of  public  health  or  sani- 
tation; he  summed  up  the  knowledge  of  his  day  concerning 
hygiene  under  six  headings,  viz. :  Air,  Aliment,  Exercise 
and  Rest,  Sleep  and  Wakefulness,  Repletion  and  Evacua- 
tion, and  the  Passions  and  Affections  of  the  Mind;  and  he 
even  pointed  out  that  thelre  must  be  an  exact  balance 
between  food  and  exercise,  and  that  ' (  disease  would  result 
from  excess  in  either  direction."  The  excellence  of  the 


20       ^  MANUAL  OF  HYGIENE  AND  SANITATION. 

Mosaic  code  of  the  Hebrews  is  acknowledged  by  all  sani- 
tary authorities,  and  its  effects  are  seen  to  this  day  in  the 
comparative  longevity  of  the  race.  The  Greeks  cultivated 
to  the  extreme  both  the  physical  and  mental  faculties,  and 
had  for  their  motto  A  sound  mind  in  a  sound  body.  The 
Romans,  in  their  aqueducts  for  conveying  water  to  the 
city  and  in  the  Cloaca  Maxima,  have  left  some  wonderful 
examples  of  sanitary  engineering,  which  are,  in  certain 
respects,  not  yet  surpassed. 

The  development  of  hygiene  as  a  science,  however,  has 
been  within  comparatively  recent  years.  Perhaps  the 
first  great  impulse  among  English-speaking  peoples, 
especially  in  matters  pertaining  to  sanitation  or  u  State 
medicine,"  can  be  traced  to  the  labors  of  Dr.  William  Farr, 
and  to  the  establishment,  through  his  efforts,  of  the 
British  Registrar-General's  office  in  1838.  Since  then 
the  task  of  determining  the  principles  and  laws  of  health 
has  been  carried  on  with  unflagging  zeal  by  workers 
both  here  and  abroad,  and  within  the  last  dozen  of  years 
or  so  the  knowledge  gained  in  the  new  study  of  the  bacteria, 
especially  that  regarding  the  causation  and  true  nature  of 
infectious  diseases,  has  furnished  us  with  a  wealth  of  facts 
with  and  by  which  we  may  make  the  foundations  of  our 
science  more  unchangeable  and  lasting. 

It  would  be  wrong,  however,  to  give  the  impression  that 
hygiene  is,  as  yet,  an  exact  science.  While  it  is  rapidly 
attracting  popular  notice  and  attention,  and  has  attained 
within  comparatively  recent  years  a  dignity  that  it  did  not 
hitherto  have  in  this  new  world,  it  is  already  on  a  some- 
what firmer  basis  in  the  old.  But  the  brightest  minds  of 
the  day  are  still  busy  with  many  of  its  problems,  and  facts 
and  laws  are  being  made  clear  that  more  firmly  fix  or 
altogether  change  some  of  our  beliefs  and  our  practice. 


INTRO  D  UCTION.  21 

Especially  is  such  new  knowledge  to  be  sought  for  in  the 
study  of  the  prevention  of  disease,  the  domain  of  bacteri- 
ology, parasitic  diseases,  and  the  chemistry  of  the  animal 
alkaloids  and  kindred  compounds. 

Perhaps  a  few  statistics  will  help  one  to  realize  that  the 
study  is  not  in  vain,  and  that  the  promise  of  the  future  is 
even  more  brilliant  than  the  results  and  achievements  of 
the  past.  Three  centuries  ago  the  death-rate  of  London 
was  more  than  eighty  per  thousand ;  now  it  is  about 
twenty.  It  is  computed  that  in  the  eighteenth  century — 
the  one  preceding  the  introduction  of  vaccination — fifty 
millions  of  people  were  killed  in  Europe  by  smallpox 
alone;  now  it  is  practically  almost  an  extinct  disease.  In 
1872  Sir  John  Simon  estimated  "  that  the  deaths  which 
occur  in  England  are  fully  a  third  more  numerous  than 
they  would  be  if  our  existing  knowledge  of  the  chief 
causes  of  disease  were  reasonably  well  applied  throughout 
the  country,  and  that  of  deaths  which  in  this  sense  may 
be  called  preventable  the  average  yearly  number  in  Eng-. 
land  and  Wales  is  about  120,000."  In  confirmation  of 
the  accuracy  of  this  statement,  official  reports  show  that 
the  average  death-rate  of  England  and  Wales  from  1862 
to  1871  was  22.6  per  1000,  and  that  of  1881  was  18.9, 
this  giving  a  saving  of  92,000  lives  annually;  while  for 
1889  the  death-rate  was  17.9,  indicating  a  yearly  saving 
of  at  least  125,000  lives,  even  with  the  correction  for  the 
lowered  birth-rate.  Moreover,  the  death-rate  from  the 
seven  principal  zymotic  (infectious)  diseases  had  dropped 
from  an  average  of  4. 11  for  1&61  to  1870  to  2.40  for  1881 
to  1885,  and  that  of  typhoid  fever  from  0.39  per  1000  in 
1869  to  0.137  in  1892.  This  for  England  and  Wales.  In 
Munich  from  1866  to  1881  the  average  yearly  hospital 
admissions  of  typhoid-fever  cases  were  594,  or  3.32  per 


22       A  MANUAL  OF  HYGIENE  AND  SANITATION. 

1000  of  population,  and  the  average  deaths  from  this  dis- 
ease were  208  or  1.15  per  1000.  From  1881  to*1888, 
following  the  introduction  of  improved  systems  of  sewer- 
age, the  average  hospital  admissions  (typhoid)  were  104, 
or  only  0.42  per  1000,  and  the  average  deaths  were  40, 
or  only  0.16  per  1000  of  population. 

In  this  country  a  like  improvement  is  to  be  noted, 
though  it  is  only  within  the  last  few  decades  that 
much  attention  has  been  given  to  sanitary  affairs.  The 
death-rate  of  most  of  our  cities  is  being  progressively 
lowered,  though  the  populations  are  constantly  increased 
by  large  numbers  of  ignorant  and  uncleanly  immigrants 
from  abroad.  Improved  sanitary  laws  are  being  enacted 
and  enforced,  streets  better  paved  and  cared  for,  houses 
more  properly  constructed  and  ventilated,  more  attention 
given  to  isolating  the  sick  and  protecting  the  well,  and 
the  people  in  general  are  widely  awakening  to  the  impor- 
tance of  improving  as  well  as  maintaining  the  public 
health.  New  York  has  reduced  her  death-rate  within  the 
last  decade  (1887  to  1897)  from  26.32  to  19.50;  Chicago, 
from  20.27  to  13.46;  Philadelphia,  from  21.85  to  18.72.1 

Nevertheless,  there  is  still  much  to  be  done.  Tubercu- 
losis, which  causes  from  one-seventh  to  one-fourth  of  all 
the  deaths  in  the  world,  is  practically  a  preventable  dis- 
ease, and  we  now  not  only  know  its  cause,  but  also  have 
efficient  means  for  a  cure  in  a  large  proportion  of  cases,  as 
well  as  for  its  general  prevention.  So  with  a  number  of 
the  other  infectious  diseases.  Every  day  marks  an  increase 
in  our  knowledge  of  their  etiology  and  the  securing  of 
immunity  from  them,  and  not  only  must  physicians  make 
use  of  this  knowledge  as  they  acquire  it,  and  use  their 

1  From  the  Board  of  Health  Reports  of  the  respective  cities. 


INTR  OD  UCTION.  23 

utmost  endeavors  to  secure  the  enactment  and  enforcement 
of  sanitary  laws  and  regulations,  but  they  must  realize 
that  a  large  part  of  their  work  lies  in  the  enlightenment 
and  education  of  the  people  in  all  matters  pertaining  to 
the  public  health.1 

In  the  preparation  of  a  study  like  the  one  on  which  we 
are  about  to  enter  there  is  some  question  as  to  just  what 
may  be  the  most  advantageous  order  and  arrangement  of 
the  subjects  to  be  treated.  For  instance,  it  would  be 
interesting  to  discuss  our  science  in  its  relation,  in  turn, 
to  the  individual,  the  household,  and  the  people  in  general 
— that  is,  personal,  domestic,  and  public  hygiene;  and  to 
show  wherein  the  treatment  of  these  subdivisions  is  sim- 
ilar and  wherein  they  differ;  and  such  a  threefold  consid- 
eration would  be  not  only  logical,  but  extremely  instructive. 

However,  since  the  bacteria  have  been  shown  to  have  so 
important  a  part  in  many  of  the  processes  intimately  con- 
nected with  health  or  disease,  it  will  doubtless  be  advisable 
to  devote  the  opening  chapter  to  a  brief  review  of  the 
science  of  bacteriology.  This  done,  it  seems  to  the  writer 
that  we  shall,  as  beginners,  obtain  a  more  comprehensive 
and  thorough  view  of  our  subject  if  we  pursue  a  method 
somewhat  as  follows  :  First,  to  discuss  air,  water,  and  food 
— three  things  absolutely  essential  to  life — in  all  the  vary- 
ing conditions  and  circumstances  under  which  they  may 
affect  the  bodily  welfare,  either  for  good  or  bad,  of  the 
individual  or  of  the  community.  Then,  to  take  up  in 


1  It  is  encouraging  to  find  that,  although  10  per  cent,  of  the  whole  number  of 
deaths  recorded  in  Philadelphia  in  1895  'were  caused  by  consumption,  a  progres- 
sive and  marked  lowering  of  the  death-rate  from  this  disease  in  that  city  is  taking 
place,  and  that,  notwithstanding  an  increase  in  population  of  almost  40  per  cent., 
the  fatalities  from  this,  disease  are  actually  less  in  number  than  they  were  sixteen 
or  seventeen  years  ago.  For  example,  the  deaths  from  pulmonary  tuberculosis  in 
1880  numbered  2692.  a  rate  of  3.178  to  the  1000  living ;  while  in  1897  there  were 
only  2388  deaths,  or  a  rate  of  less  than  2.1  to  1000  living. 


24       A  MANUAL  OF  HYGIENE  AND  SANITATION. 

such  order  as  may  seem  best  the  other  themes,  whose  con- 
sideration is  only  a  degree  less  important  than  the  above 
in  the  preservation  of  health  and  prevention  of  disease; 
such  as  climatology,  habitations,  disinfection  and  quaran- 
tine, disposal  of  sewage,  clothing,  exercise,  school  hygiene, 
etc.  In  this  way,  while  the  whole  ground  may  not  be 
covered,  the  importance  of  the  various  subdivisions  may 
be  estimated  in  their  relationship  to  one  another,  and  we 
shall  be  the  better  prepared  to  pursue  the  study  as  oppor- 
tunity may  offer  in  the  future. 

It  is  doubtless  in  place  just  here  to  review  briefly  the 
reasons  why  it  is  the  special  duty  of  the  physician  to  be 
able  to  recognize  and  remove  insanitary  conditions  wherever 
they  may  be  found,  and  why  he  should  make  particular 
and  constant  study  of  this  science  in  all  its  branches  and 
developments. 

Every  true  physician  soon  finds  that  the  respect  and 
affection  of  his  patients  and  associates  are  worth  far  more 
than  mere  mercenary  gain,  and  that  his  highest  aim  should 
be  to  prevent  disease  rather  than  simply  to  cure  it.  And, 
though  this  may  seem  to  militate  against  his  personal 
interests,  he  is  unworthy  the  name  of  physician  if  his 
object  and  purpose  is  solely  or  primarily  to  make  money. 
However,  the  observer  quickly  learns  that  in  a  community 
kept  in  good  health  and  hygienic  condition  there  will 
always  be  more  or  less  need  of  a  doctor's  services,  in  spite 
of  every  effort  to  prevent  sickness,  and  that  such  a  com- 
munity will  pay  more  promptly  and  more  liberally  for 
such  services  than  one  in  which  all  sanitary  precautions 
are  neglected.  Health  means  ability  to  work  and  to  earn 
good  wages ;  and  a  healthy  community  means  more  busi- 
ness, more  money,  and  more  comforts.  Moreover,  as  a 
rule,  good  wages  ensure  prompt  and  cheerful  payment  of 


IN  TROD  UCTION.  25 

the  doctor's  bills,  as  well  as  of  others.  We  may  note  here 
the  close  relations  existing  between  sanitary  science  and 
social  and  political  economy — a  relationship  which  is  very 
intimate,  as  we  shall  see  from  time  to  time  in  our  work, 
for  as  the  physical  condition  of  a  people  is  bettered  it 
becomes  more  easy  and  more  certain  that  they  will  like- 
wise improve  both  mentally  and  morally. 

Again,  though  the  science  of  hygiene  and  sanitation  is 
comparatively  a  new  one,  public  attention  is  being  strongly 
directed  toward  it,  not  only  because  it  vitally  interests 
every  one,  but  because  new  discoveries  and  new  applica- 
tions of  the  laws  pertaining  to  it  are  being  constantly 
made,  which  are,  in  time,  swiftly  given  to  the  world  by 
both  the  scientific  and  the  popular  press.  This  creates  a 
demand  for  first-class  teachers,  which  demand  is  bound  to 
increase  in  the  near  future  and  promises  materially  to 
exceed  the  supply.  In  fact,  within  a  very  few  years  not 
only  the  medical,  but  the  academic  and  scientific  colleges 
of  the  country  will  be  compelled  by  powerful  public  opin- 
ion to  establish  in  their  faculties  well-equipped  and  well- 
endowed  chairs  of  hygiene  and  sanitary  science,  and  it 
will  be  from  the  ranks  of  the  educated  physicians  of  the 
country  that  these  teachers  must  naturally  come.  It  will 
not  be  long  before  the  people  in  general  realize  that  it  is 
as  important  that  the  college  student  or  graduate  be 
instructed  how  to  do  his  part  in  taking  care  of  the  health 
of  himself,  his  future  family,  and  the  community  in  which 
he  is  to  reside,  as  that  he  shall  be  well  read  in  the  abstract 
principles  of  theology  or  the  classics  of  dead  languages. 

So,  also,  considerably  more  time  and  attention  than  are 
now  accorded  to  it  should  be  given  to  hygiene  in  the  work 
of  the  various  normal  schools  for  teachers.  The  gradu- 
ates of  these  schools  will  have  much  of  the  physical  as 


26       A  MANUAL  OF  HYGIENE  AND  SANITATION. 

well  as  the  mental  welfare  of  thousands  of  young  and 
growing  children  in  their  keeping,  and  it  is  unquestionably 
their  duty  to  prevent  or  obviate  the  ills  of  school-life  as 
far  as  is  in  their  power,  and  to  give  instruction  in  and 
inculcate  habits  of  living  which  will  continually  tend  to 
improve  and  preserve  the  physical  health  of  those  under 
their  care.  One  need  scarcely  intimate  that,  as  the  subject 
and  its  study  are  comparatively  new  and  the  demand  for 
instructors  is  likely  to  be  in  excess  of  the  supply,  the 
recompense  of  the  latter  should  be  accordingly  lucrative. 

Lastly,  the  time  has  come  when  a  physician  must  neces- 
sarily have  a  knowledge  of  hygiene,  preventive  medicine, 
and  sanitary  science.  Many  States  require  as  thorough 
examinations  in  this  as  in  any  other  branch  of  medicine, 
before  granting  the  right  to  practice  within  their  bounda- 
ries. So  do  the  army,  navy,  and  marine  hospital  services 
of  the  Government.  Moreover,  the  people  generally,  as 
I  have  intimated,  are  awakening  to  an  interest  in  sanitary 
matters  and  the  prevention  of  disease,  and  expect  their 
physicians  to  be  well  versed  on  all  pertaining  subjects;  if 
they  find  a  doctor  lacking  in  knowledge  or  interest  in  this 
respect,  they  are  apt  to  think,  rightly  or  wrongly,  that 
he  will  also  be  deficient  in  the  other  branches  of  medicine. 

Happily  these  causes  all  combine  to  place  preventive  on 
the  same  high  plane  with  curative  medicine,  and  the  time 
is  fast  passing  in  which  the  chair  of  hygiene  fails  to  have 
a  primary  place  in  any  thorough  medical  school. 

It  is  evident  that  the  successful  physician  and  practical 
student  of  hygiene  must  have  a  thorough  knowledge  of 
three  things  :  1.  Health  and  its  laws;  how  to  obtain  and 
preserve  it.  This,  of  course,  implies  a  knowledge  of  the 
human  body  and  its  functions,  viz.,  of  anatomy,  physiol- 
ogy, and  physiological  chemistry.  2.  He  must  study  dis- 


INTR  OD  UCTION.  27 

ease  and  its  causes  and  nature.  He  must  also  understand 
the  distinction  between  diseases  due  to  causes  external 
and  those  due  to  causes  internal  to  the  body;  and  that, 
while  some  of  these  causes  may  be  prevented  or  modified, 
others,  with  our  present  knowledge,  may  not  be  so  readily 
overcome.  3.  He  must  be  conversant  with  and  know 
how  to  use  the  therapeutic  agents,  both  preventive  and 
curative,  that  he  has  at  his  disposal,  including  not  only 
drugs,  but  also  all  substances  and  forces  that  he  can  make 
efficacious  to  his  purpose.  The  workman  must  know  his 
tools  to  be  able  to  use  them  intelligently. 

Health  is  "  that  condition  of  the  body  and  its  organs 
necessary  to  the  proper  performance  of  their  normal  func- 
tions/7 and  disease  may  be  defined  as  "  a  condition  of  the 
body  marked  by  inharmonious  action  of  one  or  more  of 
the  various  tissues  or  organs,  owing  to  abnormal  con- 
dition or  structural  change."  It  is,  accordingly,  well  to 
consider  briefly  the  nature  and  causes  of  disease,  that  we 
may  the  better  understand  the  influence  upon  its  preven- 
tion or  production  of  all  those  varying  phases  and  con- 
ditions of  our  .environment  which  we  hope  to  study  in 
our  work. 

Disease  is  an  entity,  not  a  spiritual  thing;  a  condition, 
not  a  theory.  Consequently,  it  is  to  be  combated  with 
matter,  force,  and  physical  means,  though  not  necessarily 
with  violence.  In  fact,  when  once  we  understand  the 
minuteness  and  delicate  structure  of  the  ultimate  cells  and 
tissues  affected,  we  realize  that  oftentimes  the  gentlest 
application  of  the  forces  and  means  employed  may  be  the 
most  helpful  and  efficient.  But  when  one  has  seen  the 
ravages  caused  by  it,  as  revealed  in  the  pathological  labo- 
ratory and  at  autopsies,  not  to  speak  of  its  manifestations 
in  the  living,  as  seen  in  the  sick-room  and  in  hospitals,  I 


28       A  MANUAL  OF  HYGIENE  AND  SANITATION. 

am  sure  that  he  cannot  logically,  or  even  for  a  moment, 
give  credence  to  those  who  proclaim  that  it  can  be  dissi- 
pated by  the  mere  action  of  mind  or  of  faith ;  nor  to  those 
others  who  declare  that  by  subdividing  and  diluting  and 
subdividing  again  a  single  grain  of  substance,  whether 
primarily  powerful  or  inert,  you  endow  it  with  a  miracu- 
lous power  to  remove  the  "ills  that  flesh  is  heir  to." 
Virchow  gave  a  priceless  boon  to  modern  medicine  in  his 
theory  of  cellular  pathology  and  in  showing  its  superiority 
to  the  old  humoral  theories  and  a  priori  reasoning.  He 
wrote  "whatever  outside  of  a  cell  acts  upon  it  (abnormally) 
works  a  mechanical  or  chemical  change  within  it,  which 
change  is  disorder  or  disease." 

For  convenience  sake,  diseases  may  be  divided  into  two 
main  classes,  somewhat  different  in  their  origin,  nature, 
and  character,  although  the  dividing  line  between  the 
classes  is  not  always  as  marked  as  it  would  appear  to  be 
at  first  sight.  The  first  class  arises  within  the  body 
through  some  alteration  or  disturbance  of  nutrition  and 
assimilation,  or  of  function,  and  may  be  called  autogenetic. 
The  second  class  comprises  those  which,  are  due  to  causes 
from  without,  favored,  it  may  be,  by  either  internal  or 
external  predisposing  conditions,  but  of  necessity  depend- 
ing upon  the  reception  or  inoculation  of  the  special  cause, 
which  cause  has  the  power  of  reproduction  and  develop- 
ment, of  vitality  and  virulence.  Such  diseases  are  called 
contagious,  infectious,  specific,  or  zymotic. 

A  third  class  might  also  be  indicated,  which  would 
include  those  maladies  which  are  almost  purely  psychical 
and  whose  symptoms  are  largely  notional  and  the  result  of 
perverted  imagination.  But  it  is  a  question  whether  the 
primary  cause  of  such  disorders  is  not  an  altered  and 
abnormal  nutrition  of  the  general  nervous  economy  of  the 


INTR  OD  UCTION.  29 

body,  or  else  the  reflex  manifestations  of  irritative  distur- 
bances of  distant  organs. 

In  the  first  class,  with  our  present  knowledge,  we  should 
place  such  maladies  as  rheumatism,  gout,  diabetes,  neuras- 
thenia, etc. ;  while  into  the  second  will  obviously  fall  all 
that  are  now  known  to  be  due  to  living  "germs"  or 
organisms,  such  as  cholera,  typhoid  fever,  malaria,  etc. 
However,  we  must  not  overlook  the  numerous 'impulses 
often  given  to  the  causation  of  certain  members  of  the 
second  class  by  faulty  conditions  of  nutrition  or  assimila- 
tion, as  is  especially  exemplified  in  many  cases  of  tubercu- 
losis. The  character  of  the  soil  may  influence  the  growth 
and  product  of  the  plant  almost  as  much  as  the  species 
itself. 

Prophylaxis  is  "  the  use  of  hygienic  or  other  precautions 
conducive  to  the  prevention  of  disease;77  or  it  may  be 
defined  as  (t  a  series  of  methods  or  procedures  whereby 
disease  is  restricted  and  prevented  by  suppressing  or 
removing  its  predisposing  conditions,  and  destroying  or 
modifying  the  exciting  causes.77  Its  first  function,  of  sup- 
pressing or  removing  predisposing  conditions,  is  accom- 
plished by  sanitation';  the  second,  that  of  destroying  or 
modifying  exciting  causes,  is  carried  out  by  disinfection. 
The  words  "predisposing  conditions77  should  be  used 
instead  of  "predisposing  causes,77  because  these  condi- 
tions cannot  in  themselves  originate  a  disease,  though 
they  may  make  the  system  more  susceptible  to  the  excit- 
ing causes  of  a  disease. 

As  we  have,  as  yet,  very  little  definite  knowledge  of  the 
real  nature  of  the  exciting  causes  of  autogenetic  diseases, 
they  being  developed  and  elaborated  within  the  body,  and 
as  disinfection,  or  the  destruction  and  modification  of  these 
exciting  causes,  is  an  essential  feature  of  prophylaxis,  we, 


30       ^  MANUAL  OF  HYGIENE  AND  SANITATION. 

at  present,  naturally  look  for  more  satisfactory  results  in 
the  application  of  prophylaxis  to  the  second  class  of  dis- 
eases; but  it  does  not  prevent  or  restrict  the  employment 
of  certain  prophylactic  measures  in  regard  to  the  first  class, 
such  as  the  selection  of  proper  diet,  clothing,  climate,  etc. , 
and  the  removal  or  counteracting  of  all  causes  favoring 
malnutrition.  We  may,  therefore,  say  that  sanitation  is 
the  defensive,  disinfection  the  aggressive  part  of  prophy- 
laxis. 

To  remove  and  suppress  predisposing  conditions  and  to 
prepare  the  body  to  resist  and  repel  the  action  of  exciting 
causes,  we  must  not  only  strengthen  its  resisting  powers, 
but  also  make  all  external  media  as  favorable  to  it  and  as 
hostile  to  the  exciting  causes  as  possible. 

The  resisting  powers  of  the  body  must  lie  in  the  indi- 
vidual cells  and  tissues  of  the  body,  including  the  vital 
fluids,  and  it  is  but  natural  to  suppose  that  this  repellent 
action  to  noxious  substances  is  best  performed  when  the 
cells  and  tissues  are  in  most  perfect  health  and  most  vig- 
orous. This  is  not  only  good  logic,  but  all  our  experience 
and  scientific  research  go  to  show  that  it  has  a  firm  foun- 
dation in  fact. 

We  shall  soon  learn  that  purity  of  the  external  media 
and  environment  of  the  body  is  essential  to  its  health  and 
that  of  its  component  tissues,  and  that  conditions  of 
impurity  in  these  media  predispose  to  disease.  We  shall 
also  learn  that  a  proper  and  sufficient  supply  of  whole- 
some food  is  essential  to  health,  and  that  certain  other 
factors,  as  sex,  age,  clothing,  climate,  etc.,  may  or  may  not 
predispose  to  disease.  In  other  words,  if  we  strengthen 
the  resisting  powers  of  the  system  to  the  fullest  extent  and 
remove  all  predisposing  .conditions,  in  all  probability  the 
exciting  causes  will  be  inoperative,  and  there  will  be  no 


INTRODUCTION.  31 

incurrence  of  disease.  This  is  the  essence  of  sanitation : 
to  secure  perfect  health,  to  increase  the  inherent  power  to 
resist  noxious  and  harmful  influences,  and  to  make  all  the 
surroundings  and  environments  of  the  body  pure  and  free 
from  depressing  factors.  This  applies  equally  to  both  classes 
of  disease;  for  with  healthy  cells  and  proper  food  there 
will  not  be  faulty  nutrition  and  assimilation  and  the  con- 
sequent production  of  the  exciting  causes  of  autogenetic 
disease;  and  with  a  vigorous  resistance  and  pure  sur- 
roundings there  is  little  opportunity  for  the  germs  of  con- 
tagious maladies  to  obtain  a  foothold  within  the  system 
long  enough  to  reproduce  themselves  and  cause  their  char- 
acteristic diseases.  The  best  means  of  preventing  disease 
is  to  learn  and  apply  the  best  means  of  attaining  and 
retaining  a  healthy  and  vigorous  state  of  the  system,  viz., 
to  learn  and  observe  the  laws  of  hygiene. 


CHAPTEE    II. 

B  ACTERIOLOGY. 

THE  increase  in  the  knowledge  concerning  the  lowest 
forms  of  life,  and  the  discovery  within  recent  years  that 
these  often  have  a  truly  causative  action  in  the  excitation 
of  many  maladies,  have  greatly  facilitated  the  study  of  the 
causes  and  prevention  of  disease.  In  fact,  it  is  largely  to 
this  advance  in  knowledge  and  to  the  confirmation  of  the 
germ  theory  that  much  of  the  success  of  modern  hygiene 
and  sanitation  is  due. 

The  unicellular,  vegetal  micro-organisms  divide  them- 
selves into  two  general  classes  with  respect  to  their  manner 
of  reproduction,  viz.,  those  that  multiply  by  budding — the 
bladomyceteSj  and  those  that  increase  by  simple  division  or 
fission — the  schizomyedes.  In  the  former  class  we  have 
the  hyphomycetes  or  mould-fungi,  and  the  saccharomycetes 
or  yeasts,  examples  of  these  being  familiar  to  every  one. 
However,  it  is  with  the  fission-fungi  or  bacteria,  as  they 
are  now  more  generally  known,  that  we  are  most  con- 
cerned as  sanitarians,  since  they  practically  include  almost 
all  those  vegetal  micro-organisms  that  are  more  or  less 
closely  connected  with  the  production  of  disease,  compara- 
tively few  of  the  yeasts  and  moulds  being  pathogenic,  and 
then  only  indirectly  or  in  a  minor  degree. 

Bacteriology,  then,  is  the  science  of  those  unicellular, 
vegetal  micro-organisms  that  multiply  by  direct  division 
(fission),  or,  as  occasionally  happens,  by  the  development 
of  spores.  Its  study  consists  in  the  examination  by  means 


BACTERIOLOGY.  33 

of  the  microscope  of  the  form  and  method  of  growth 
of  these  minute  plants,  in  their  artificial  cultivation  on 
or  in  suitable  media,  and  in  the  determination  of  the  effects 
of  the  inoculation  of  pure  cultures  upon  animals.  To  this 
may  be  added  another  field  of  research  that  gives  promise 
of  rapid  development  in  the  near  future,  viz.,  the  study 
of  the  chemistry  of  the  bacterial  products  and  the  reac- 
tions produced  by  them  in  culture  media  and  in  living 
tissues. 

Although  more  than  two  centuries  have  elapsed  since 
the  discovery  of  the  bacteria  by  Leeuwenhoek  (about 
1680),  and  though  Plenciz  advanced  what  is  practically 
the  germ  theory  of  to-day  as  early  as  1762,  most  of  our 
knowledge  concerning  the  physiology,  methods  of  cultiva- 
tion, and  differentiation  of  the  bacteria  have  been  acquired 
within  the  last  fifteen  or  twenty  years.  It  is  true  that 
some  advance  had  been  made  in  sterilization,  and  that 
Cohn,  by  establishing  the  fact  of  spore-formation,  demol- 
ished the  last  arguments  in  favor  of  spontaneous  genera- 
tion, and  confirmed  the  science  of  bacteriology;  but  until 
the  few  years  just  preceding  the  last  decade  we  had  but 
little  knowledge  as  to  the  means  of  separating  and  isolating 
the  different  species  and  making  pure  cultures,  or  of  pre- 
paring culture  media,  staining,  etc. 

As  already  intimated,  the  bacteria  are  unicellular  organ- 
isms, usually  multiplying  by  a.  process  of  cell-elongation 
and  fission.  Being  deprived  of .  chlorophyll,  they  cannot 
absorb  and  decompose  carbonic  acid  and  ammonia,  as  do 
the  higher  plants;  but  require-for  their  growth  and  nutri- 
tion organic  matter  —  usually  soluble  albumin  —  in  the 
presence  of  moisture.  Hence  they  must  be  either  sapro- 
phytes or  parasites.  As  the  combination  of  albuminous 
organic  matter  and  water  is  extremely  common,  so  the 

3  . 


34    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

distribution  of  the  bacteria  over  the  earth  is  widespread 
and  practically  universal. 

Some  of  the  bacteria  may,  however,  under  adverse  con- 
ditions, such  as  lack  of  nutriment  or  moisture,  too  alkaline 
or  acid  a  medium,  extremes  of  temperature,  etc.,  or,  on  the 
other  hand,  as  a  result  of  the  attainment  of  a  stage  of  maxi- 
mum development,  produce  spores  which  are  much  more 
strongly  resistant  to  deleterious  influences  than  the  bacteria 
themselves.  In  this  way  the  spore-forming  bacilli  may 


FIG.  1. 


Micrococci  (gonococcus)  in  pus-cells.    X  1000. 

often  survive  the  action  of  disinfectants  or  other  agencies 
that  are  sufficient  to  destroy  other  bacteria.  Upon  the 
resumption  or  recurrence  of  favorable  conditions  the  spores 
develop  into  cells  similar  in  form  and  nature  to  their  parent 
cells. 

It  is  to  be  remembered  that  spores  do  not  reproduce 
spores,  and  that  "  a  single  cell  produces  but  one  spore." 

1  Abbott :  "  Principles  of  Bacteriology,"  1st  ed.,  p.  31. 


BACTERIOLOGY.  35 

Under  the  microscope  the  spores  are  seen  as  highly  refrac- 
tive, spherical  bodies  that  stain  with  difficulty,  and  evi- 
dently have  a  very  resistant  envelope,  probably  of  cellu- 
lose. The  interior  of  bacteria  and  spores  is  protoplasm. 
So  far  as  we  positively  know  at  this  time,  only  certain 
bacilli  form  spores,  though  there  is  a  possibility  that  a 
few  of  the  spirilla  and  one  or  two  species  of  micrococci 
have  the  same  faculty. 

Again,  under  certain  peculiar  conditions  some  organisms 
may  develop  another  morphological  change,  the  so-called 


FIG.  2. 


<*~*Y\S*k&&*i</  '- 

-       -  •    SV>-V 


Tubercle  bacilli  in  sputum,    x  1000. 

involution  forms.  These  are  doubtless  pathologically  dis- 
torted cells,  with  probably  less  than  normal  resisting 
powers,  but  which  will  again  revert  to  the  normal  under 
favorable  conditions,  providing  the  unfavorable  environ- 
ment does  not  first  kill  them. 

Lastly,  there  are  times  when  certain  individuals  of  a 


36       A  MANUAL  OF  HYGIENE  AND  SANITATION. 

species  seem  to  have  departed  from  the  typical  form,  these 
departures  being  only  different  phases  in  the  normal  devel- 
opment. Thus  a  young  bacillus  may  be  shorter  than  the 
adult  and  look  much  like  a  coccus,  or  a  coccus  about  to 
undergo  division  may  be  oval  in  shape  and  considerably 
larger  than  the  quiescent  members  of  its  species.  But 
one  form  of  bacteria  never  permanently  takes  that  of 
another — micrococci  are  always  inicrococci,  bacilli  always 
bacilli,  etc. 

A  thoroughly  scientific  classification  of  the  bacteria  is 
scarcely  possible  as  yet,  owing  to  our  incomplete  knowledge 
of  their  character,  method  of  growth,  physiology,  etc. 
However,  there  are  a  number  of  ways  in  which  we  may 
subdivide  them,  none  of  them  exactly  scientific,  perhaps, 
but  still  sufficiently  accurate  and  convenient  for  our  pur- 
pose. If  we  consider  them  as  to  form  we  have  :  (a) 
micrococci,  spherical  in  shape;  (6)  bacilli,  which  have  one 
diameter  longer  than  another;  and  (c)  spirilla,  spirals  or 
segments  of  spirals.  We  shall  have  more  to  say  hereafter 
of  the  characteristics  of  each  of  these  subdivisions.  Accord- 
ingly as  they  live  best  with  or  without  air  or  oxygen  they 
are  aerobic  or  anaerobic.  Again,  they  may  be  named 
according  to  their  product;  e.  g.,  some  produce  colors, 
chromogenic,  others  pus,  pyogenic,  etc.  Lastly,  they  are 
either  saprophytic  or  parasitic.  Some  of  the  micrococci 
are  named  according  to  the  manner  in  which  they  grow. 
If  in  pairs,  they  are  called  diplococci;  in  fours,  tetracocci; 
in  threads,  streptococci,  etc.  Groups  or  masses  of  micro- 
cocci  or  bacilli  held  together  by  a  gelatinous  substance 
are  called  zooglea.  With  one  or  two  exceptions  we  know 
but  little  about  the  spirilla.  The  germ  of  cholera — the 
comma  bacillus  (?) — belongs  to  this  class,  and  the  cause  of 
relapsing  fever  is  also  probably  a  spirillum. 


BACTERIOLOGY.  37 

Most  of  the  bacteria  thrive  best  in  culture  media  that 
are  neutral  or  only  slightly  alkaline,  though  a  few  species 
seem  to  do  better  in  slightly  acid  surroundings.  So,  also, 
they  do  best  at  temperatures  ranging  between  20°  and  40° 
C.  (68°  and  104°  F.),  though  they  may  grow  between  5° 
and  43°  C.  (41°  and  109.4°  F.).  Any  marked  deviation 
in  the  culture  media  from  the  neutral  point  or  continued 
exposure  to  extremes  of  temperature  may  either  check  the 


Spirillum  of  Asiatic  cholera.    X  1000. 

growth  of  the  organisms  altogether,  and  eventually  destroy 
them,  or  may  cause  spore  formation,  or  the  production  of 
involution  forms,  or  may  cause  a  change  in  the  composi- 
tion and  the  character  of  the  chemical  products  which  the 
bacteria  normally  produce.  This  also  holds  good  with 
respect  to  any  other  condition  or  substance  that  may  be 
deleterious  to  the  bacteria  in  their  normal  state;  and  we 
shall  see  that  this  is  important  as  having  a  decided  influ- 


38       A  MANUAL  OF  HYGIENE  AND  SANITATION. 

ence  in  lessening  the  virulence  of  pathogenic  bacteria  and 
bringing  about  a  condition  of  immunity  to  their  attacks. 

As  it  is  rare  to  find  isolated  individual  species  anywhere 
except  in  artificially  prepared  pure  cultures,  it  is  evident 
that  we  must  devise  some  way  of  separating  the  different 
kinds  of  organisms  one  from  another.  This  is  best  accom- 
plished by  the  method  suggested  by  Koch,  viz.,  to  intro- 
duce the  mixed  kinds  into  some  melted  culture  medium, 


FIG.  4. 


Bacilli  of  hog  cholera  showing  flagellae.    X  1000. 

like  nutrient  gelatine,  which  solidifies  on  cooling,  but 
whose  melting  point  is  not  sufficiently  high  to  destroy  the 
vitality  of  the  germs.  If  the  fluid  be  then  shaken,  the 
various  species  will  be  distributed  through  it,  and  upon 
cooling  each  individual  or  group  of  individuals  of  the 
same  kind  (zooglea)  will  be  fixed  in  its  place  and  become 
the  starting  point  of  a  colony  of  that  special  kind;  and  if 
the  gelatine  be  poured  out  before  cooling  upon  sterilized 


BACTERIOLOGY.  39 

glass  plates  or  into  flat  (Petri)  dishes  (Fig.  5),  the  subse- 
quent work  of  counting,  examining,  and  making  cultures 
from  the  colonies  will  be  greatly  facilitated.  Moreover, 
this  process  may  be  repeated  until  absolutely  pure  cultures 
are  obtained  of  each  species  in  the  original  mixture. 


FIG.  5. 


Petri  double  dish,  now  generally  used  instead  of  plates. 

Special  care  must  be  taken  in  this,  as  in  all  other  bacte- 
riological methods  or  operations,  to  prevent  contamination 
of  our  cultures,  media,  or  apparatus  by  other  organisms, 
which  are  almost  omnipresent,  and  which  would  prevent 
any  accurate  results  or  deductions  whatever,  were  they  not 
rigidly  excluded  or  destroyed.  Obviously,  we  may  not 
use  the  ordinary  chemical  disinfectants  or  antiseptics  as 
a  means  of  destroying  and  removing  these  interfering 
microbes,  for  by  their  action  we  should  destroy  or  check 
the  growth  of  the  bacteria  we  desire  to  cultivate  ;  but  must 
sterilize  by  heat  all  the  articles  we  use,  together  with  their 
contents.  This,  if  properly  done,  does  not  affect  the  nutri- 
ent properties  of  the  culture  media,  while  it  removes  the 
danger  of  subsequent  contamination. 

In  sterilizing  we  may  use  either  dry  or  moist  heat,  the 
latter  being  by  far  more  preferable  in  most  cases  (Figs. 
6  and  7),  since  to  be  effectual  it  does  not  require  so  high 
a  temperature  nor  so  long  a  time  as  does  the  former. 
Moist  heat,  especially  in  the  form  of  steam,  is  more  pene- 


40 


MANUAL  OF  HYGIENE  AND  SANITATION. 


trating  than  dry  heat;  beside,  the  dry  heat  requires  to  be 
of  so  high  a  temperature  that  it  may  spoil  for  culture  pur- 
poses such  substances  as  the  nutrient  gelatine.  Glassware 
and  the  like,  however,  may  be  quickly  and  advantageously 
sterilized  by  dry  heat.  On  the  other  hand,  certain  sub- 


FIG.  6. 


Steam  sterilizer,  pattern  of  Koch. 

stances,  like  blood-serum,  are  ruined  by  moist  heat  con- 
tinued long  enough  to  destroy  the  spores  possibly  present, 
as  the  latter  need  a  much  higher  temperature  to  sterilize 
them  than  the  former.  So  we  resort  to  fractional  steril- 
ization in  such  cases,  exposing  our  materials  for  only  a 
short  time  to  a  temperature  just  sufficient  to  destroy  the 
bacteria,  repeating  the  process  after  an  interval  which  is 
sufficient  to  allow  the  spores  to  develop  into  bacteria,  say, 


BACTERIOLOGY.  41 

twenty-four  hours,  and  sterilizing  again  a  third  time  after 
a  like  interval.  Having  thus  sterilized  the  culture  media 
and  apparatus,  we  prevent  the  access  of  contaminating 
germs  to  the  interior  of  our  tubes  and  vessels  by  plugs  of 
sterilized  cotton-wool,  covering  these,  when  necessary,  with 
rubber  caps  to  prevent  the  evaporation  of  fluids  or  of 
moisture  from  the  gelatine,  etc. 


FIG.  7. 


Arnold  steam  sterilizer. 


As  a  basis  for  a  number  of  culture  media,  we  may  use 
beef -broth  or  bouillon,  which  is  a  fluid  especially  favorable 
to  bacterial  growth,  in  that  it  contains  an  abundance  of 
albumin  in  solution.  When  a  solid  medium  is  desired, 
either  gelatine  or  agar-agar  (a 'sort  of  vegetable  gelatine 
from  Japan)  may  be  added  to  this,  giving  us  nutrient  gela- 
tine and  nutrient  agar-agar.  Of  these,  the  gelatine  has  a 
melting-point  below  the  temperature  of  the  human  body, 


42      A  MANUAL  OF  HYGIENE  AND  SANITATION. 

while  the  agar  has  not,  so  we  have  to  employ  the  latter 
when  it  is  desired  to  cultivate  germs  that  grow  best  at  the 
body-temperature,  although  the  development  of  most  bac- 
teria is  usually  more  rapid  and  characteristic  upon  the 
gelatine.  Sterilized  and  solidified  blood-serum  is  also  used 
for  the  cultivation  of  certain  organisms,  like  the  diphtheria 
bacillus,  and  there  are  certain  others  which  can  only  be 
differentiated  by  their  difference  in  growth  upon  boiled 
potato,  milk,  etc. 

The  differentiation  of  the  various  species  of  bacteria  is 
to  be  made  by  noting  their  appearance  and  form  under  the 


FIG.  8. 


Kuled  square  for  counting  colonies. 


microscope,  whether  they  are  motile  or  not,  how  they  take 
different  stains,  etc.;  by  observing  their  methods  of  growth 
in  or  upon  different  culture  media,  whether  they  are 
aerobic  or  anaerobic  or  facultative;  at  what  temperatures 
they  do  best,  etc.,  and  finally  by  studying  their  action  and 
the  action  of  the  substances  they  produce  upon  living 
animals.  In  this  way  we  may  determine  the  characteris- 
tics of  each  individual  or  species,  and  will  eventually  have 
the  groundwork  and  material  for  a  strictly  scientific  classi- 
fication of  the  schizomycetes.  For  example,  the  organisms 
causing  suppuration  are  micrococci,  occurring  in  clusters 
(staphylococci)  or  in  chains  (streptococci);  the  cause  of 
typhoid  fever  is  a  bacillus,  and  the  cholera  germ  belongs 


BACTERIOLOGY. 


43 


to  the  spirilla.  The  tubercle  bacillus  stains  with  marked 
difficulty,  but  wheu  stained  is  not  readily  decolorized  by 
a  weak  solution  of  nitric  acid  as  are  almost  all  other  bacilli. 
Some  bacteria  liquefy  nutrient  gelatine,  others  do  not,  and 
almost  none  liquefy  agar-agar.  This  liquefaction  is  not 


FIG.  9. 


Pocket-case  containing  sterilized  culture  tubes,  platinum  needle,  and  small 
alcohol  lamp  used  for  obtaining  cultures  for  diagnosis,  etc. 


a  melting,  but  rather  a  probable  peptonization,  since  the 
gelatin  will  not  solidify  again  after  it  occurs,  as  it  will  after 
being  subjected  to  moderate  warming.  Again,  some  bac- 
teria produce  one  color  or  chemical  substance  in  the  pres- 
ence of  oxygen,  and  another  in  its  absence;  some  only  pro- 
duce color  in  the  light,  others  only  in  the  dark,  etc.  Finally, 


44       A  MANUAL  OF  HYGIENE  AND  SANITATION. 

as  we  already  know,  different  pathogenic  microbes  produce 
different  maladies  when  inoculated  in  animals  or  human 
beings,  and  the  same  germ  may  produce  different  results 
in  animals  of  different  species  or  families.1 

The  subdivision  of  the  bacteria  into  saprophytes  and 
parasites  has  been  already  noted,  and  it  must  be  remem- 
bered that  not  all  of  these  microscopic  plants  are  disease- 
producers,  much  the  larger  proportion,  in  fact,  being  bene- 
factors rather  than  otherwise  to  the  human  race. 

The  function  of  the  saprophytic  organisms  is  to  break 
up  dead  organic  matter  into  simpler  chemical  compounds 
and  ultimately  into  carbonic  acid,  ammonia,  and  water; 
these  latter  substances  being  once  more  utilized  in  the 
nutrition  of  the  higher  forms  of  vegetable  life,  which  are, 
in  turn,  necessary  to  the  existence  of  animal  life  upon  the 
globe.  Indeed,  it  is  only  when  the  student  of  hygiene 
fairly  realizes  the  great  scope  of  the  functions  of  these 
minute  but  almost  omnipresent  scavengers  that  he  can 
comprehend  the  important  part  they  play  in  the  purifica- 
tion of  our  environment.  In  the  air  they  possibly  help 
the  oxygen  to  destroy  the  harmful  effluvia  and  exhalations 
of  men  and  animals  and  the  floating  debris  of  organic 
substances;  in  the  soil,  the  common  receptacle  of  the 
wastes  and  refuse  of  vital  activity,  they  quickly  and  con- 
tinually convert  these  noxious  additions  into  foods  of  the 
highest  value  to  growing  plants;  in  running  streams  and 
quiet  pools  they  are  of  the  greatest  importance  in  the 
removal  of  the  dangerous  impurities  washed  from  the 
surface  of  the  land  or  recklessly  discharged  from  human 
habitations,  factories,  and  the  like.  And  not  o'nly  do  the 
saprophytes  help  mankind  in  this  way,  but  members  of 

1  See  Kenwood's  "  Hygienic  Laboratory,"  pp.  466-70  ;  also  McFarland's  "  Path- 
ogenic Bacteria,"  pp.  46-57. 


BA  CTERIOL  OGY.  45 

the  class  are  beneficent  in  many  others.  For  example, 
they  enable  those  plants,  the  leguminosae,  which  yield  us 
the  largest  supply  of  vegetable  proteids,  to  derive  much 
of  their  nitrogen  almost  directly  from  the  atmosphere; 
they  have  much  to  do  with  the  flavor  and  value  of  dairy 
products,  and  new  uses  in  which  they  may  be  employed 
in  the  domestic  or  commercial  affairs  of  life  are  being 
announced  from  day  to  day.  And  thus  we  find  this  class 
of  the  bacteria,  which  comprises  by  far  the  greater  number 
of  species,  to  be  our  beuef actors  and  indispensable  servants 
both  in  preventing  the  accumulation  of  noxious  and  harm- 
ful substances  upon  the  earth  and  in  really  helping  to 
produce  the  food  which  we  eat. 

The  parasitic  bacteria,  on  the  other  hand,  have  their 
habitat  in  or  upon  highly  organized  living  matter,  and 
exist  at  its  expense.  They  also  produce  in  their  growth 
substances  called  toxins,  that  are  either  locally  or  generally 
poisonous  or  harmful  to  the  organism  that  is  their  host. 
It  is  needless  to  say  that  it  is  in  this  class  that  we  find  the 
disease  germs,  or  pathogens,  as  some  would  call  them. 
It  should  not  be  forgotten,  however,  that  the  saprophytes, 
in  the  decomposition  of  complex  organic  bodies,  may  also 
produce  ptomaines,  more  or  less  toxic  to  animal  life.  Of 
these  latter  we  may  instance  as  good  examples  the  dan- 
gerous tyrotoxicon,  a  by  no  means  uncommon  product  in 
the  decomposition  of  milk,  ice-cream,  etc.,  the  cadaveric 
poisoning  of  the  dissecting-room,  etc.  But,  while  these 
ptomaines  are  more  or  less  characteristic  of  the  respective 
bacteria  that  produce  them,  each  varies  in  its  composition 
and  properties  according  to  the  substance  upon  or  in  which 
it  is  produced. 

We  say  that  an  organism  is  optional  when  it  is  at  one 
time  a  saprophyte  and  at  another  a  parasite,  or  at  one  time 


46       A  MANUAL  OF  HYGIENE  AND  SANITATION. 

aerobic  and  again  anaerobic;  and  that  it  is  obligate  when 
it  has  not  this  property  of  changing  its  nature  according 
to  surrounding  conditions. 

Considering  for  the  present  the  pathogenic  bacteria 
alone,  we  are  naturally  brought  to  the  discussion  of  the 
gerni  theory,  which  is,  that  the  exciting  cause  of  each 
contagious  or  infectious  disease  is  some  specific  parasitic 
organism,  and  that  these  diseases  are  communicated  only 
by  the  transference  to  and  development  of  the  specific 
parasite  or  germ  within  or  upon  the  infected  individual. 
Consequently,  such  diseases  are  transmitted  from  one  per- 
son to  another,  or,  in  some  cases,  from  animals  to  men,  or 
vice  versa,  by  means  of  these  micro-organisms,  and  the 
transference  is  by  the  air,  water,  food,  or  other  fomites,  or 
by  direct  contact.  It  is  evident  that,  if  facts  and  knowl- 
edge establish  the  truth  of  this  theory,  the  prevention  of 
infectious  diseases  is  greatly  simplified,  and  becomes 
merely  a  matter  of  combining  effective  sanitation,  of 
which  we  have  spoken,  with  the  destruction  of  the  specific 
exciting  causes,  viz.,  disinfection.  Nor  is  it  essential  that 
we  any  longer  make  the  distinction  between  the  terms 
contagious,  infectious,  zymotic,  and  specific,  that  formerly 
obtained,  but  all  may  be  practically  used  synonymously. 
The  first  of  these  terms  used  to  be  applied  to  those  diseases 
which  were  thought  to  be  transmitted  by  direct  contact 
only,  and  "  infectious ' 7  to  those  in  which  the  transmis- 
sion was  by  fomites.  But  we  now  know  that  germs  of 
the  former  class  may  be  transmitted  by  air,  water,  food, 
etc.,  and  of  the  latter  by  direct  contact,  though  the  reverse 
is  what  usually  happens  in  the  respective  classes.  The 
term  "  zymotic"  was  formerly  applied  to  those  diseases 
occurring  in  epidemics,  and  supposed  to  be  due  to  fermen- 
tative processes;  if  used  at  all,  it  should  be  given  to  any 


BACTERIOLOGY.  47 

disease  due  to  a  living  germ.  The  term  <f  specific  "  should 
only  be  given  to  those  maladies  which  have  a  specific  origin 
— i.  e.j  which  have  been  proved  to  be  due  solely  to  a  single 
organism. 

That  most  communicable  diseases  are  due  to  such  germs 
or  kindred  animal  organisms  is  more  than  probable,  and, 
while  there  are  some  in  which  it  has  not  been  fully  proved, 
it  is  scarcely  possible  that  any  of  these  may  arise  from 
insanitary  causes  without  the  presence  of  a  living  organism. 

Our  reasons  for  believing  in  the  germ  theory  are  based 
on  empirical  and  logical  facts  as  well  as  theoretical 
hypotheses.  Leaving  out,  at  present,  the  work  already 
done,  it  is  evident  that  the  matter  that  causes  a  disease, 
the  contagium,  must,  when  introduced  into  a  susceptible 
person  or  animal,  increase  in  quantity  to  an  enormous 
extent.  Note,  for  instance,  the  amount  of  positively  viru- 
lent matter  thrown  off  from  a  case  of  smallpox  or  scarlet 
fever,  and  yet  how  very  little  is  required  to  initiate  a  dis- 
ease. No  dead  chemical  substance  has  the  power  of  being 
increased  to  such  an  extent  by  simply  finding  a  lodgement 
in  a  suitable  medium.  The  poison  of  contagion,  whatever 
it  may  be,  evidently  must  have  life  and  the  power  of 
reproduction.  Moreover,  these  causes  of  disease  when 
freed  from  the  body  may  be  carried  long  distances,  and 
may  exist  for  years,  and  still  retain  their  power  for  harm, 
only  waiting  to  find  a  suitable  field  before  beginning  to 
multiply  and  cause  the  same  identical  malady  as  before. 
Such  causes  must,  therefore,  be  capable  of  entering  a  state 
in  which  vitality  is  latent  or  dormant,  and  in  which  the 
reproductive  functions  are  for  a  time  inactive.  But  we 
do  know  that  the  spores  of  many  bacteria,  and  sometimes 
the  bacteria  themselves,  may  be  carried  long  distances, 
kept  long  periods  of  time,  and  even  exposed  to  consider- 


48       A  MANUAL  OF  HYGIENE  AND  SANITATION. 

able  extremes  of  temperature,  without  being  killed  or 
losing  their  power  of  reproduction  and  rapid  multiplica- 
tion. Again,  we  know  that  substances  that  are  poisonous 
to  or  that  prevent  the  development  of  these  bacteria  and 
kindred  low  forms  of  life,  do,  when  properly  applied  or 
used,  prevent  or  remove  the  danger  of  contagion. 

There  is  also  in  the  development  and  progress  of  any 
infectious  diseases  a  direct  analogy  to  the  phenomena  of 
fermentation,  whose  causative  organisms  are  of  the  same 
order  as  these  which  we  are  considering;  the  same  rapid 
multiplication  of  cells  in  suitable  media  at  proper  tempera-, 
tures,  a  period  of  incubation,  and  then  changes  in  the  cul- 
ture medium,  which,  after  going  on  to  a  certain  extent, 
check  the  further  growth  of  the  organism  in  that  medium. 
What  it  is  in  the  medium  that  checks  the  growth  of  the 
germ,  we  may  not  be  able  to  determine  a  priori,  but  we 
may  assume  it  to  be  something  hostile  to  the  contagium,  as 
alcohol  above  a  certain  percentage  is  hostile  to  the  yeast- 
cell. 

Lastly,  if  the  proof  of  Koch's  postulates  is  essential 
to  the  acceptance  of  a  given  micro-organism  as  the  cause  of 
a  given  disease;  on  the  other  hand,  we  must  believe  that 
a  certain  germ  is  a  cause  of  that  disease,  if  not  the  only 
one,  if  these  postulates  be  proven  about  that  germ  in  con- 
nection with  the  disease. 

To  determine  whether  a  certain  organism  is  or  is  not 
pathogenic  it  is  necessary  to  experiment  on  living  animals. 
To  do  this  we  must  use  pure  cultures  of  the  organism  and 
carry  out  all  our  processes,  including  inoculations  and 
autopsies,  under  strictly  antiseptic  precautions.  We  must 
examine  the  blood  and  various  tissues  of  a  diseased  animal 
microscopically;  if  bacteria  be  present  in  any  of  these,  we 
must  make  cultures  from  them,  and  if  more  than  one  kind 


BACTERIOLOGY.  49 

of  bacteria  be  present,  the  various  kinds  must  be  isolated 
and  pure  cultures  made  from  each  kind.  When  a  pure 
culture  is  at  last  obtained,  it  is  studied  both  microscop- 
ically and  as  to  its  characteristics  on  various  media  and  at 
different  temperatures.  Finally,  healthy  animals  known 
to  be  susceptible  to  the  disease  are  inoculated  from  the 
pure  culture,  and,  after  the  period  of  incubation,  carefully 
watched  for  symptoms  of  the  disease  in  question.  Should 
these  manifest  themselves,  the  animal  is  killed  and  the 
blood  and  tissues  carefully  examined  for  the  inoculated 
organisms. 

The  postulates  of  Koch,  which  are  necessary  to  prove 
that  a  germ  is  the  cause  of  a  given  disease,  are:  1.  The 
micro-organism  must  be  found  in  the  blood,  lymph,  or 
diseased  tissues  of  a  person  or  animal  sick  or  dead  of  the 
disease.  2.  The  micro-organism  must  be  isolated  from 
the  blood,  lymph,  or  tissues  and  cultivated  in  suitable 
media  outside  of  the  animal  body.  These  cultivations 
must  be  carried  on  through  several  generations  until  a 
pure  culture  of  the  germ  is  obtained.  3.  A  pure  culture 
thus  obtained  must,  when  introduced  into  a  healthy  animal, 
produce  the  disease  in  question.  4.  In  the  inoculated  ani- 
mal the  same  organism  must  again  be  found. 

In  the  cases  of  many  diseases  peculiar  to  human  beings 
alone  the  third  condition  must  remain  undetermined  and 
our  chain  of  proof  be  broken,  because  we  cannot  endanger 
human  health  or  life  by  our  inoculations.  But  in  diseases 
common  to  men  and  animals  the  experiments  necessary  can 
be  completely  carried  out,  and  where  a  germ  can  be  proved 
to  be  the  cause,  according  to  these  postulates,  of  the  malady 
in  animals,  we  can  also  fairly  conclude  that  it  is  the  cause 
of  the  same  disease  in  human  beings.  The  specific  germs  of 
a  number  of  maladies  common  to  man  and  beast  have  thus 


50      A  MANUAL  OF  HYGIENE  AND  SANITATION. 

been  determined,  together  with  those  of  a  large  number  of 
affections  peculiar  to  animals  alone. 

After  infection  or  the  reception  of  the  contagium  by  a 
susceptible  animal  there  is  a  period  of  incubation  before 
the  manifestation  of  the  characteristic  symptoms  of  the 
disease,  which  period  is  variable  according  to  the  kind  of 
germ,  and  during  which  the  micro-organisms  are  rapidly 
increasing  in  numbers  and  their  consequent  power  for  evil. 
After  the  pathological  process  is  well  under  way  we  shall 
find  one  of  two  conditions  existing,  viz.,  that  "  in  which 
the  blood  is  the  chief  field  of  activity  of  the  organisms," 
and  the  vessels  of  the  victim  are  swarming  with  the 
microbes — in  other  words,  a  true  septicaemia;  or  else  one 
where  "  the  poisonous  results  are  not  necessarily  accompa- 
nied by  the  growth  of  organisms  in  the  tissues,"  these 
latter,  in  all  likelihood,  not  extending  beyond  the  lym- 
phatic glands  nearest  to  the  point  of  inoculation — i.  e., 
a  toxcemia.  A  good  example  of  the  former  condition  is 
furnished  by  a  case  of  anthrax  or  of  pyaemia,  and  of  the 
latter,  in  diphtheria.  However,  we  shall  find  in  either 
condition  that  if  we  isolate  the  peculiar  product  or  toxin 
of  the  specific  germ,  either  from  artificial  growths  upon 
culture  media,  or  from  the  blood  or  tissues  of  an  animal 
sick  or  dead  of  the  disease,  and  inoculate  this  into  a  sus- 
ceptible animal,  the  general  symptoms  and  results  pro- 
duced are  practically  the  same  as  in  an  ordinary  case  of 
the  disease.  This  goes  to  prove  that  the  products  of  patho- 
genic bacteria  are  toxic  in  character  and  poisonous  to  the 
tissues,  either  locally  or  generally,  and  that  infection  must 
be  accordingly  a  chemical  and  toxicological  process. 
Another  point  to  note  just  here  is  that  these  toxins  are 

i  Abbott,  loc.  cit. 


BACTERIOLOGY.  51 

apparently  harmful  to  the  bacteria  themselves  whenever 
they  exceed  a  certain  amount,  as  is  shown  by  the  fact  that 
most  of  the  infectious  diseases  are  self -limiting  and  by  the 
cessation  of  growth  and  even  the  death  of  the  germs  in  the 
various  culture  media  after  a  certain  length  of  time.  It  is 
but  right  to  state,  however,  that  there  is  another  possible 
explanation  of  this  latter  phenomenon,  viz.,  an  increase  in 
the  resistance  of  the  infected  body  to  the  action  of  the 
germs  and  toxins,  and,  in  the  case  of  culture  media,  the 
marked  change  in  reaction  caused  by  the  bacterial  products. 

Having  thus  obtained  some  knowledge  of  the  exciting 
causes  of  contagious  diseases  and  of  how  they  act,  one  of 
the  most  important  considerations  is  in  relation  to  the  pre- 
vention of  the  incurrence  of  these  diseases  by  the  well, 
and  to  the  antagonizing  or  checking  of  the  further  action 
of  the  cause  in  those  already  infected.  It  is  well  to  dis- 
infect and  destroy  disease-germs  whenever  and  wherever 
it  is  possible  to  do  so,  but  it  will  be  still  better  so  to 
strengthen  and  fortify  the  human  body  that  the  microbes, 
even  though  received  into  it,  will  be  unable  to  attack  it  or 
do  it  harm.  That  we  have  the  means  of  producing  such 
immunity  in  the  case  of  one  disease,  at  least,  is  well  shown 
by  the  history  of  vaccination,  and  the  abundant  work  of 
numerous  investigators  in  recent  years  indicates  that  the 
promise  of  similar  results  in  many  other  maladies  is  by 
no  means  vain.  Certain  it  is  that  many  animals  and,  in 
some  cases,  men  have  been  rendered  apparently  immune 
to  other  fatal  diseases,  and  the  indications  point  to  the 
probability  that  the  human  race  .will  shortly  have  the  same 
protection  against  most  of  the  contagious  maladies  that  it 
now  has  against  smallpox. 

With  the  knowledge  that  immunity  to  infectious  dis- 
eases may  be  produced  accidentally  or  intentionally,  and 


52       ^  MANUAL  OF  HYGIENE  AND  SANITATION. 

may  be  practically  applied  without  a  definite  understand- 
ing thereof,  we  need  not  consider  the  method  whereby  the 
body  brings  about  such  immunity.  Nevertheless,  several 
theories  have  been  advanced  in  the  attempt  to  explain  the 
phenomenon.  Of  these  two  have  been  practically  dis- 
proved, viz.,  the  exhaustion  theory  of  Pasteur,  which  was 
that  the  pathogenic  germs  in  their  process  of  growth  in 
the  body  removed  some  material  from  the  latter  necessary 
to  their  existence;  and  the  diametrically  opposite  retention 
theory  of  Chauveau,  which  was  that  the  germs  produced 
some  substance  which  gave  immunity  as  long  as  it  was 
retained  in  the  tissues.  On  the  other  hand,  there  are  still 
strong  adherents  to  both  the  phagocytosis  theory  of  Metch- 
nikoff  and  the  humoral  theory  of  Biichner. 

The  phagocytosis  theory  is  (t  that  immunity  against 
infection  is  essentially  a  matter  between  the  invading  bac- 
teria on  one  hand,  and  the  leucocytes  of  the  tissues  on  the 
other;  that  during  the  first  attack  of  the  disease  the  white 
blood-corpuscles  gain  a  tolerance  to  the  poisons  of  the 
bacteria,  and  so  are  able  to  resist  the  next  incursions  of 
the  enemy. "  Biichner  has  apparently  shown  that  the 
blood-plasma,  especially  that  of  immune  animals,  is  actu- 
ally bactericidal  to  many  virulent  germs,  and  he  attributes 
this  effect  to  the  presence  in  the  fluid  of  certain  proteid 
substances  akin  to  globulin.  These  he  terms  alexins,  from 
a  Greek  word  meaning  to  protect.  Further,  he  believes 
that  they  act  chemically  in  causing  the  death  of  the  disease 
germs,  and  that  the  increased  amount  of  alexins  in  the 
blood  of  those  who  have  acquired  immunity  is  brought 
about  by  a  stimulation  or  "  reactive  change'7  in  certain 
cells  due  to  the  presence  of  the  bacteria  or  their  products. 
Moreover,  this  humoral  theory  serves  to  account  for  the 
natural  immunity  possessed  by  some  individuals  and  ani- 


BACTERIOLOGY.  53 

mals,  their  body  juices  presumably  containing,  through 
some  cause  or  other,  an  extra  quantity  of  the  protective 
proteids. 

There  is,  however,  another  theory,  that  of  the  anti- 
toxins, which,  in  view  of  recent  developments  and  the  fact 
that  it  is  the  most  capable  of  practical  application,  is  prob- 
ably the  most  important  of  all.  It  is  well  known  that  the 
human  system  has  the  power  of  tolerating  or  accommodat- 
ing itself  to  the  action  of  almost  any  toxic  substance — pro- 
vided the  latter  be  administered  in  sufficiently  minute  doses 
gradually  increased  until  it  can  in  time  withstand  quan- 
tities that  would  quickly  prove  fatal  to  one  unaccustomed 
to  the  poison.  Ehrlich  has  further  shown  that,  with  the 
alkaloids  of  certain  higher  plants,  after  a  certain  degree  of 
tolerance  is  attained  the  administration  of  the  drug  may 
be  much  more  rapidly  increased,  and  that  while  up  to  this 
point  no  change  occurs  in  the  blood,  now,  when  the  toler- 
ance becomes  so  much  exaggerated,  a  new  substance  is 
produced  which  is  capable  of  neutralizing  the  poison  in 
that  individual  not  only,  but  also  in  others  into  whose 
blood  it  may  be  introduced.  Many  experiments  have 
shown  that  this  same  production  of  antidotal  or  antago- 
nizing substances  may  be  brought  about  by  the  slow 
administration  of  the  toxins  of  pathogenic  bacteria — some- 
thing not  hard  to  understand  when  we  remember  that  the 
bacterial  toxins  are  just  as  much  the  products  of  plant-life 
as  are  the  alkaloids  that  Ehrlich  used,  and  very  much  like 
the  latter  in  formula  or  composition. 

On  the  other  hand,  the  antitoxins,  as  these  new  sub- 
stances antidotal  to  the  toxins  are  called,  have  been  found 
to  be  albuminoid  in  character  and  very  similar  to  the 
nuclei ns.  In  fact,  some  attempts  have  been  made  to  em- 
ploy the  latter  in  place  of  or  in  conjunction  with  the  anti- 


54      A  MANUAL  OF  HYGIENE  AND  SANITATION. 

toxins,  with  results  which  have  not  been  altogether  without 
success  and  to  which  reference  may  hereafter  be  made. 

Much  credit  must  be  given  to  the  labors  of  Behring, 
B-oux,  Kitasato,  and  others,  for  the  development  of  prac- 
tical methods  of  using  the  anitoxins,  methods  which  are 
now  recognized  as  eminently  proper  and  even  superior  to 
any  others  in  the  treatment  of  some  of  the  most  virulent 
diseases.  The  great  reduction  in  the  mortality  from  one 
disease  alone — diphtheria — already  attained  through  the 
application  of  this  treatment  almost  exceeds  expectation 
and  belief,  and  the  promise  seems  now  to  be  that  the 
results  with  respect  to  tetanus  and  cholera  and  other  deadly 
maladies  will  be  equally  brilliant  and  add  further  glory 
to  this  new  science  of  bacteriology. 

To  some  it  may  seem  that  either  the  humoral  or  the 
antitoxin  theory  is  identical  with  the  discarded  retention- 
theory  of  Chauveau ;  but  it  should  be  noted  that,  according 
to  the  latter,  the  invading  microbes  themselves  produce  the 
antidote  or  antagonizing  substance,  while  Biichner's  theory 
attributes  this  production  to  the  integral  cells  of  the  body, 
which  furnish  the  alexins  normally  in  minute  quantities  to 
the  blood,  and  insists  that  the  latter  are  germicidal  to  the 
bacteria  themselves;  and,  on  the  other  hand,  the  antitoxins, 
though  produced  by  body-cells  like  the  alexins,  act  chemi- 
cally in  neutralizing  the  bacterial  poisons,  and  are  depen- 
dent upon  the  prior  presence  in  the  body  of  the  toxins  and 
are  a  result  of  its  acquired  tolerance  to  the  latter.  With 
alexins  or  antitoxins  it  is  evident  that  the  immunity  will 
last  as  long  as  these  substances  remain  in  the  blood. 

Nor  is  there  any  reason  why  the  phagocytosis,  humoral, 
and  antitoxin  theories  should  not  mutually  support  rather 
than  tend  to  discredit  one  another.  There  seems  to  be 
good  evidence  of  the  phenomena  upon  which  each  of  the 


BACTERIOLOGY,  55 

three  is  based,  and,  even  with  our  present  incomplete 
knowledge  of  the  blood  and  its  component  parts,  it  is  not 
difficult  to  conceive  that  while  the  alexins,  and  later  the 
antitoxins,  protect  the  leucocytes  by  respectively  weaken- 
ing the  vitality  of  the  microbes  and  neutralizing  their 
products,  the  leucocytes,  thus  guarded  and  in  full  vigor, 
attack  and  make  way  with  the  bacteria,  which  have  lost 
their  virulence  and  power  for  evil.  In  other  words,  if  the 
production  of  the  toxins  of  an  infectious  malady  is  not 
too  rapid,  all  three  of  these  agents  may  combine  to  over- 
come the  enemy  and  not  only  to  limit  the  disease  but  also 
to  give  subsequent  immunity  for  a  more  or  less  prolonged 
period. 

Nevertheless,  experience  will  continue  to  show  that, 
whether  one  or  all  of  these  theories  may  be  finally 
accepted,  or  whether  new  methods  by  which  the  body 
protects  itself  may  be  discovered,  sanitation  and  a  con- 
dition of  perfect  health  throughout  the  system  are  of  the 
utmost  importance  in  warding  off  attacks  of  or  securing 
immunity  from  any  of  the  pathogenic  organisms,  and  in 
withstanding  their  ravages,  should  disease  be  incurred. 
A  sound  body,  therefore,  is  a  most  vitally  active  and  not 
a  passive  agent  for  the  prevention  of  such  diseases. 

Within  a  comparatively  short  space  of  time  the  anti- 
toxins have  been  discovered,  tried,  and  apparently  practi- 
cally adopted  by  the  medical  profession  of  the  civilized 
world  as  a  safe  and  efficient  means  for  the  prevention  or 
alleviation  and  cure  of  several  of  our  most  dreaded  dis- 
eases. A  short  account  of  the  usual  methods  of  preparing 
them  will,  therefore,  probably  not  be  uninteresting. 

In  the  first  place,  it  is  necessary  that  the  toxin  of  the 
disease  should  be  produced,  which  is  commonly  done  by 
growing  the  specific  organism  in  a  peptone-bouillon. 


56       A  MANUAL  OF  HYGIENE  AND  SANITATION. 

When  this  has  attained  a  powerful  and  definite  virulency, 
as  determined  by  the  effect  on  small  animals  of  known 
weight  when  inoculated  with  it,  the  organisms  are  de- 
stroyed by  some  germicide,  such  as  trikresol,  or  more 
commonly  the  bouillon  containing  the  toxins  is  filtered  care- 
fully to  remove  the  germs.  A  small  quantity,  say  one  cubic 

FIG.  10. 


Filter  for  removing  bacteria  from  fluid  culture  media. 

centimetre,  of  the  filtered  bouillon  is  then  injected  into  a 
large  animal,  such  as  the  horse,  which  should  be  in  good 
health  and,  preferably,  should  have  been  tested  previously 
by  inoculations  of  tuberculin  and  mallein  to  eliminate  the 
possibility  of  the  presence  of  tuberculosis  or  glanders. 
The  animal  manifests  the  disturbances  peculiar  to  the  dis- 
ease in  question  for  a  few  days,  but  usually  in  a  minor 
degree,  since  the  dose  was  quite  small  in  proportion  to  its 
weight;  as  soon  as  recovery  is  evident,  another  inoculation 
of  an  increased  dose  is  made,  and  so  on  until  experiment 
shows  that  the  animal  can  withstand  practically  an  unlim- 
ited dose  of  the  toxic  bouillon  and  one  which  would  have 


BACTERIOLOGY.  57 

been  quickly  fatal  before  the  first  inoculation.  This  is 
evidence  that  the  antitoxin  exists  in  approximately  suffi- 
cient degree  in  the  blood-serum.  A  quantity  of  blood  is 
then  taken  with  the  strictest  antiseptic  precautions  from 
the  jugular  or  .other  large  vein  of  the  animal,  the  latter 
returned  to  its  quarters,  and  the  blood  set  aside  on  ice  to 
coagulate.  This  done,  the  clear  serum  containing  the 
antitoxin  is  drawn  off,  and  to  it  is  added  a  small  quantity 
of  trikresol  or  other  harmless  preservative. 

It  is  now  necessary  to  determine  the  strength  of  the 
serum.  The  fatal  dose  of  toxin  for  guinea-pigs  is  readily 
found  by  experiment.  Behring,  therefore,  suggested,  in  the 
case  of  diphtheria  antitoxin,  that  the  immunizing  unit 
be  taken  to  be  1  c.c.  of  a  serum  of  which  0.1  c.c.  would 
prevent  oedema  and  death  in  guinea-pigs  when  injected 
simultaneously  with  ten  times  the  fatal  dose  of  toxin.  In 
other  words,  the  immunizing  unit  was  to  be  sufficient  to 
overcome  one  hundred  times  the  amount  of  the  toxin 
required  to  kill  a  guinea-pig. 

FIG.  11. 


Roux  aseptic  hypodermic  syringe  for  administering  antitoxin. 

The  antitoxin  serums  now  administered  are,  however, 
much  stronger  than  this  normal  serum  of  Behring's,  10 
c.c.,  the  amount  usually  injected,  containing  from  600 
to  2500  or  even  more  immunizing  units,  the  weaker 
strength  being  used  for  immunizing  those  who  have  not 
as  yet  incurred  the  disease.  Much  depends  upon  the 
early  use  of  the  specific  antitoxin  in  cases  of  diphtheria, 
and  probably  also  for  the  other  diseases  for  which  this 
method  of  treatment  will  be  found  valuable.  It  is  not 


58       A  MANUAL  OF  HYGIENE  AND  SANITATION. 

to  be  supposed  that  the  remedy  has  any  power  to  repair 
the  organic  lesions  which  have  been  caused  by  the  action 
of  the  powerful  toxins.  That  the  antitoxin  treatment  is 
invaluable  cannot  be  doubted.  The  statistics  of  Prof. 
Welch,  of  Johns  Hopkins  Hospital,  founded  on  a  very  large 
number  of  diphtheria  cases,  "  show  an  apparent  reduction 
of  case-mortality  of  55.8  per  cent.,"  and  where  the  appli- 
cation was  made  in  the  first  three  days  of  the  disease  the 
mortality  was  only  8.5  per  cent,  in  over  1100  cases,  as 
against  a  mortality  of  30  per  cent,  or  more  under  former 
methods  of  treatment.  Another  interesting  report  is  that 
of  the  Chicago  Department  of  Health  for  1896.  In  that 
city  in  that  year  there  were  2436  cases  of  true  diphtheria 
verified  bacteriologically.  The  antitoxin  was  adminis- 
tered to  2302  of  these,  with  a  resultant  mortality  of  only 
6.56  per  cent.,  or  151  deaths.  Moreover,  2016  other 
persons  exposed  to  the  disease  were  inoculated  with  the 
antitoxin  in  order  to  immunize  them,  and  of  these  only 
14  subsequently  contracted  the  malady,  and  none  died. 
Further  comment  seems  unnecessary. 

Another  practical  method  of  securing  immunity,  advo- 
cated and  employed  by  several  noted  investigators,  is  as 
follows :  To  produce,  by  cultivating  the  pathogenic  bac- 
teria under  abnormal  conditions,  toxins  of  much  less  than 
normal  virulence,  and  then,  after  filtration  or  sterilization 
of  the  latter  in  order  to  isolate  them  absolutely  from  the 
causative  microbes,  to  make  a  series  of  inoculations  of  pro- 
gressively increasing  strength,  and  thus  directly  bring 
about  a  state  of  accommodation  to  or  protection  against  the 
germ  and  its  toxin  without  serious  risk  to  the  subject. 


CHAPTER    III. 

THE   ATMOSPHERE — AIR. 

THE  composition  of  the  atmosphere  surrounding  the 
earth  is  remarkably  uniform.  It  is  practically  always  the 
same  everywhere,  provided  no  obstacle  be  interposed  to 
the  action  of  those  natural  forces  by  which  this  uniformity 
is  maintained.  This  atmosphere  is  estimated  to  be  about 
forty  miles  in  depth,  and  its  weight-pressure,  of  which  we 
have  a  visible  manifestation  in  the  action  of  the  barom- 
eter, upon  the  total  surface  of  the  adult  human  body  is 
equivalent  to  that  of  about  fourteen  tons.  Any  consid- 
erable variation  in  this  pressure  may  give  rise  to  distur- 
bances of  health  more  or  less  serious,  such  as  the  cardiac 
derangements  and  "mountain  sickness'7  experienced  by 
strangers  visiting  high  altitudes,  or  the  "  caisson  disease  " 
of  those  who  work  in  a  compressed  atmosphere.  In  fact, 
it  is  not  improbable  that  some  of  the  vague  disturbances 
of  comfort  to  which  a  large  class  of  persons  are  subject  will 
hereafter  be  found  to  be  due  to  the  minor  variations  in  this 
pressure  which  are  constantly  occurring  everywhere. 

The  average  composition  of  the  air  in  its  normal  state 
is  about  as  follows  :  Oxygen,  20.96  per  cent,  by  volume; 
nitrogen  and  argon,  79  per  cent.;  carbon  dioxide,  0.04 
per  cent. ;  aqueous  vapor,  the  amount  varying  with  the 
temperature;  a  trace  of  ammonia,  and  a  variable  amount 
of  ozone,  organic  matter,  sodium  salts,  etc.  The  varia- 
tion in  the  percentage  of  oxygen  may  extend  from  20.87 
in  towns  to  20.98  in  pure  mountain  air  or  far  out  at  sea; 


60       A  MANUAL  OF  HYGIENE  AND  SANITATION. 

in  the  percentage  of  CO2,  from  0.02  to  0.05.  So  far  as  we 
know  at  present,  the  nitrogen  variation  is  almost  infinitesi- 
mal. The  air  is  a  mechanical,  not  a  chemical  mixture,  and, 
as  indicated,  there  is  always  some  change  taking  place  in 
the  proportions  of  the  various  constituents.  However, 
the  mixture  is  maintained  in  its  wonderful  uniformity  by 
the  interdependent  action  of  plants  and  animals,  and  by 
the  diffusion  of  gases,  the  law  of  which  is  that  "  a  gas 
expands  into  a  space  in  which  there  is  another  gas  as 
freely  and  as  rapidly  as  if  there  were  a  vacuum/7  Though 
this  agency,  like  the  other,  is  continually  operating,  its 
results  are  greatly  facilitated  by  adventitious  air-currents 
and  by  the  application  of  heat.  When  a  gas  is  thus 
diffused  it  will  not  separate  again  from  the  others  under 
ordinary  circumstances. 

Oxygen  is  the  most  important  of  the  above  constituents. 
It  supports  all  animal  life;  oxidizes,  destroys,  and  renders 
harmless  organic  impurities,  and,  by  oxygenating  the  blood 
and  oxidizing  the  food  for  our  tissues,  gives  us  heat  and 
energy,  the  sources  of  all  our  thoughts  and  actions.  The 
supply  to  the  atmosphere  is  constantly  maintained  by  the 
higher  plant  life,  which  decomposes  carbon  dioxide  and 
gives  off  oxygen  to  the  air.  In  man  the  greatest  limit  of 
life  without  oxygen  or  air  is  about  four  minutes.  A 
decrease  in  the  proportion  of  oxygen  in  the  air  does  not 
manifest  itself  by  untoward  symptoms  until  there  is  less 
than  13  per  cent,  by  volume  ;  then,  as  it  falls  lower  and 
lower,  the  respirations  become  slower,  deeper,  and  more 
difficult,  less  oxygen  is  absorbed  by  the  blood,  and  there 
are  dyspnoea,  asphyxia,  and  death.  This  may  occur  within 
a  short  time  when  the  percentage  goes  below  8  per  cent., 
and  asphyxia  supervenes  very  rapidly  when  there  is  as 
little  as  3  per  cent,  of  oxygen. 


THE  ATMOSPHERE— AIR.  61 

The  main  function  of  the  nitrogen  of  the  atmosphere 
seems  to  be  to  act  as  a  diluent  and  to  prevent  the  too 
energetic  action  of  the  oxygen.  We  know  now,  however, 
that  by  the  aid  of  certain  bacteria  at  least  one  family  of 
plants,  the  leguminosae,  is  able  to  take  nitrogen  almost 
directly  from  the  air  and  to  store  it  up  for  animal  use  in 
the  form  of  proteids.  The  ammonia  ever  present  in  the 
air  is  also  a  source  of  nitrogen  for  some  plants. 

The  gaseous  element,  argon,  recently  discovered  by 
Lord  Kayleigh  and  Prof.  Ramsay,  comprises  about  1  per 
cent,  of  what  has  heretofore  been  considered  atmospheric 
nitrogen.  Thus  far  little  is  known  concerning  it  except 
that  its  atomic  weight  is  probably  somewhat  less  than  40, 
its  density  about  20,  and  that  it  is  very  inert,  though 
Berthelot  has  succeeded  in  making  it  combine  with  nascent 
vapors  of  benzene  under  the  influence  of  an  electrical 
discharge.  That  it  is  a  constant  component  of  the  atmos- 
phere for  some  definite  purpose  is  more  than  probable, 
but  what  this  purpose  may  be  is,  as  yet,  unknown. 

The  carbonic  acid  present  in  pure  air  is  of  no  direct  use 
to  animals,  but  is  essential  to  the  support  of  vegetable  life, 
furnishing  the  carbon  necessary  for  the  formation  of  the 
carbohydrates  and  proteids,  which  are,  next  to  water,  the 
main  constituents  of  plants.  The  proportion  of  carbonic 
acid  in  pure  air  varies  somewhat  from  time  to  time,  owing 
to  the  changing  conditions.  It  is  washed  out  of  the  air 
by  rain,  and  there  is,  therefore,  less  after  a  heavy  storm ; 
plants  absorb  it  by  day,  and  some  give  off  a  slight  quan- 
tity of  it  by  night;  the  strata  of  the  atmosphere  near  the 
ground  receive  an  excess  of  it, from  the  soil-air;  it  is  a 
constant  product  of  the  decomposition  of  organic  matter 
by  saprophytic  bacteria,  etc.  Though  heavier  than  air,  it 


62       A  MANUAL  OF  HYGIENE  AND  SANITATION. 

is  comparatively  evenly  distributed  through  the  atmosphere 
by  the  force  of  diffusion. 

The  normal  proportion  in  the  atmosphere  varies  from 
0.02  per  cent,  to  0.05  per  cent.,  but  we  may  take  the 
average  to  be  about  0.04  per  cent.  Should,  however,  any 
important  tests  of  the  amount  in-doors  be  required,  the 
percentage  in  the  out-door  air  at  that  particular  time  and 
place  should  also  be  determined  for  the  sake  of  accuracy. 
Within  the  limits  just  given  the  carbonic  acid  cannot  be 
considered  as  an  impurity  of  the  atmosphere,  for  it  is  ever 
present  in  the  air,  and  is  as  necessary  to  plant  life  as  oxy- 
gen is  to  animals.  It  is  derived  from  the  combustion  of 
carbonaceous  materials,  from  the  exhalations  and  excre- 
tions of  animals  and  men,  and,  as  was  indicated,  in  large 
measure  from  the  action  of  the  saprophytic  bacteria  and 
also  of  the  budding  fungi  upon  organic  matter.  More- 
over, any  excess  above  the  percentage  given  is  to  be  re- 
garded not  so  much  as  an  impurity  as  an  indication  that 
certain  processes  are  at  work,  which,  by  their  products, 
may  make  the  air  impure  and  unsafe  for  human  use. 

The  amount  of  aqueous  vapor  in  the  atmosphere  varies 
constantly  because  the  factors  governing  it — condensation 
and  evaporation— are  constantly  in  action,  these  depend- 
ing, of  course,  mainly  upon  the  continual  variations  in 
temperature.  There  is  probably  never  a  perfectly  dry 
air,  unless  it  is  made  so  artificially,  and  precipitation 
occurs  the  moment  the  degree  of  complete  saturation  is 
exceeded.  The  range  of  relative  humidity  is  probably 
from  30  per  cent,  to  100  per  cent.,  this  being  equivalent, 
according  to  the  temperature,  to  a  water  content  of  from 
one  to  twelve  or  fourteen  grains  to  the  cubic  foot  of  air. 
The  best  proportion  for  health  has  not  been  experimentally 


THE  ATMOSPHERE— AIR.  63 

determined,  but  is  generally  considered  to  be  from  65  to 
75  per  cent. 

In  all  normal  air  there  is  at  least  a  trace  of  ammonia, 
either  free  or  combined,  a  small  amount  of  the  salts  of 
sodium  (especially  near  the  sea)  and  of  other  minerals,  and 
a  trace  of  organic  matter.  This  last  is  part  of  the  animal 
and  vegetable  debris  of  the  earth  ;  when  it  rises  above  a 
trace  it  is  to  be  treated  as  an  impurity,  as  should  any 
excess  of  ammonia. 

Minute  particles  of  almost  every  substance  known  are 
being  constantly  thrown  off  into  the  atmosphere,  and  it  is 
only  the  unceasing  action  of  nature's  purifying  powers 
that  keeps  the  proportion  within  the  limits  of  safety  to 
the  human  race.  Solid  particles,  lifted  up  by  the  winds, 
fall  to  the  earth  again,  or,  if  organic,  are  partially  oxidized 
and  decomposed  by  the  oxygen  and  ozone.  The  gases  are 
diluted  and  diffused  so  as  to  be  no  longer  harmful,  or  are 
decomposed,  or  are  washed  back  to  the  earth  by  rain  or 
snow.  The  great  volume  of  carbonic  acid  is  kept  within 
bounds  by  the  action  of  the  vegetable  world.  The  natural 
purifiers  of  the  atmosphere,  therefore,  are  the  force  of 
gravity,  diffusion,  dilution  by  the  air  itself,  winds,  oxida- 
tion, rain,  and  the  action  of  plant  life;  arid  so  exactly  are 
these  related  to  their  work  that  never,  when  they  have 
opportunity  to  act,  does  the  composition  of  the  air  vary 
much  from  the  normal  for  any  great  length  of  time. 

The  impurities  in  the  atmosphere  that  are  especially 
liable  to  have  a  deleterious  influence  upon  health  may  be 
classed  as  follows :  1.  Suspended  matters.  2.  Gaseous 
and  semi-gaseous  substances,  including  :  3.  Those  especi- 
ally due  to  respiratory,  combustion,  and  decomposition 
processes  and  which  are  particularly  liable  to  contaminate 
the  air  of  dwellings  or  inhabited  apartments. 


64       A  MANUAL  OF  HYGIENE  AND  SANITATION. 

The  most  important  suspended  matters  are  sand,  dust, 
soot,  pollen  of  various  plants,  micro-organisms  of  all  kinds, 
particles  of  epithelia,  and  other  excreta  thrown  off  from 
animal  bodies,  and  dusts  or  finely  divided  substances  char- 
acteristic of  certain  trades  or  industries.  These  may  do 
harm  by  clogging  up  the  air  vesicles  of  the  lungs,  and  thus 
obstructing  respiration,  though  it  is  doubtful  whether  their 
action  is  ever  so  mild  or  simple;  by  their  irritant  action  upon 
the  respiratory  passages;  by  being  in  themselves  poisonous 
or  hostile  to  the  system,  or,  as  in  the 'case  of  micro-organ- 
isms, by  the  power  they  have  in  the  causation  of  disease. 
Such  germs  may  lodge  in  the  respiratory  passages  to  do 
their  harm,  or  may  be  swallowed,  and  so  cause  maladies, 
such  as  typhoid  fever  or  cholera,  which  primarily  affect 
the  digestive  tract. 

It  is,  however,  questionable  whether  pathogenic  organ- 
isms, especially  the  bacteria,  are  commonly  to  be  found 
dissociated  from  other  substances  floating  in  the  air. 
Experiments  by  Cornet  and  others  seem  to  show  that  such 
microbes  are  apt  to  be  adherent  to  dust  particles,  particu- 
larly those  of  organic  nature,  and  it  is  probable  that  free 
bacteria  could  not  long  maintain  their  vitality  in  the  out- 
door atmosphere  deprived  of  nutriment  and  exposed  to 
the  action  of  light  and  oxygen.  Beside,  they  are  so  quickly 
diluted  and  reduced  in  numbers  in  proportion  to  any 
reasonable  volume  of  air,  that  the  occasions  must  be  rare 
indeed  when  they  could  there  cause  disease.  In-doors, 
especially  where  ventilation  is  neglected,  the  case  is  differ- 
ent, and  there  is  no  doubt  that  the  air  frequently  becomes 
the  carrier  of  the  dangerous  pathogens. 

We  must  also  make  a  distinction  as  to  whether  the  other 
solid  impurities  are  found  in  the  out-door  air  or  in  enclosed 
spaces;  and,  if  in  the  latter,  whether  in  healthy  dwellings, 


THE  ATMOSPHERE-AIR.  65 

in  sick-rooms  and  hospitals,  or  in  workshops  and  factories. 
Out-of-doors,  dust,  sand,  soot,  pollen, waste  dirt  from  dwell- 
ings, street  refuse,  and  the  remains  of  plant  and  animal 
life  will  predominate;  in-doors  the  particles  will  be  more 
limited  in  variety,  but  not  in  importance.  Among  them 
will  be  epithelium  and  other  cells,  possibly  pus-corpuscles, 
hair,  bits  of  clothing,  upholstery,  food,  etc.  One  might 
also  find  arsenical  or  other  poisonous  dust  from  wall-paper 
or  paint.  In  hospitals  there  will  probably  be  pus-cells., 
mycelia,  bacteria,  etc.  Mills,  factories,  and  mines  have 
their  special  atmospheres  filled  with  particles  peculiar  to 
the  materials  or  occupation,  which  have  a  marked  effect 
for  harm,  in  many  cases,  on  the  health  of  the  workers. 

The  gaseous  and  semi-gaseous  impurities  of  most  impor- 
tance are  those  resulting  as  products  of  human  respiration 
and  cutaneous  exhalations,  as  products  of  combustion, 
peculiar  gases  from  sewer-  or  soil-air,  organic  emanations 
and  vapors  from  decomposing  animal  and  vegetable  mat- 
ter, and  the  volatile  substances  that  characterize  the  vari- 
ous atmospheres  in  and  about  gas-works,  factories,  and 
other  industries.  Chemically,  they  may  be  classified  as  the 
various  compounds  of  carbon  with  oxygen  or  hydrogen, 
and  of  these  with  sulphur,  and  as  ammonia  .compounds, 
volatilized  minerals  and  mineral  acids,  and  many  gaseous 
and  semi-gaseous  matters  of  organic  nature  but  indeter- 
minate composition. 

Inasmuch  as  certain  of  these  impurities,  viz.,  human 
exhalations,  combustion  products,  and  not  infrequently 
the  so-called  sewer-gas,  are  particularly  liable  to  be  found 
together  as  contaminants  of  the  atmosphere  of  inhabited 
rooms  and  dwellings,  it  will  be  advisable  to  consider  them 
in  a  class  by  themselves,  and  to  study  their  effect  upon 
health  both  collectively  and  singly.  The  volatile  excreta 

5 


66       A  MANUAL  OF  HYGIENE  AND  SANITATION' 

from  the  lungs  and  skin  are  carbonic  acid,  aqueous  vapor, 
and  a  considerable  amount  of  nitrogenous  organic  matter, 
to  which  the  term  " crowd-poison"  is  sometimes  given.  As 
products  of  combustion  from  the  ordinary  lighting  and 
heating  apparatus  of  dwellings  we  may  have  carbonic  acid 
(dioxide),  carbonic  oxide  (monoxide),  sulphur  dioxide,  am- 
monia (with  possibly  its  sulphide),  and  aqueous  vapor.  Of 
sewer-gas  and  soil-air  we  shall  speak  later. 

Carbonic-acid  gas,  contrary  to  the  general  opinion,  can- 
not be  said  to  be  directly  poisonous  or  harmful  to  health 
in  the  proportions  in  which  it  is  likely  to  be  found  in 
any  dwelling  or  inhabited  apartment.  Although  present 
to  the  extent  of  not  over  0.05  per  cent,  in  normal  out-door 
air,  numerous  experiments  indicate  that  both  men  and 
animals  may  inhale  much  larger  proportions  than  this  with- 
out apparent  harm,  provided  the  percentage  of  oxygen  in 
the  air  be  maintained  at  or  above  the  normal;  an  increase 
of  the  carbonic  acid  from  other  sources  than  respiration 
and  combustion  seems  to  have  no  appreciable  effect  upon 
the  system  till  it  reaches  more  than  2  per  cent. ,  and  many 
work  daily  in  atmospheres  containing  almost  this  amount 
as  a  result  of  their  peculiar  occupations,  and  dyspnoea  does 
not  begin  to  occur,  and  then  only  in  some,  until  the  per- 
centage goes  above  3  or  4  per  cent.  In  quantities  above 
these  figures  there  is  much  difference  of  opinion  as  to  the 
effect  of  the  gas  upon  the  human  economy,  and  the  writer 
is  not  aware  that  it  has  ever  been  determined  beyond 
question  as  to  just  what  percentage  is  fatal.  Prof.  Parkes 
states  the  lethal  proportion  to  be  from  5  to  10  per  cent. ; 
while  another  states  that  animals  may  be  kept  for  a  long 
time  in  an  atmosphere  in  which  there  is  a  high  percentage 
of  carbon  dioxide,  provided  the  percentage  of  oxygen  be 
increased  at  the  same  time.  Dr.  Hime  says  that  et  it  may 


THE  ATMOSPHERE— AIR.  67 

be  assumed  that  10  or  20  per  cent,  is  a  dangerous 
amount, m  but  Wilson2  shows  that  air  having  from  25 
to  30  per  cent,  may  be  inhaled  with  impunity.  It  is 
to  be  understood  that  the  above  percentages  are  all  by 
volume. 

According  to  his  size,  an  adult  man  at  rest  absorbs  from 
fifteen  to  eighteen  cubic  feet  of  oxygen  and  exhales  from 
twelve  to  fourteen  cubic  feet  of  carbonic  acid  in  twenty- 
four  hours.  Reichert3  says:  "The  amount  of  O  varies  from 
600  to  1200  grammes  (15  to  30  cubic  feet)  per  diem,  and 
that  of  CO2  from  700  to  1400  grammes  (12.5  to  25  cubic 
feet) — approximate  averages  being  about  750  grammes  of 
O  and  875  grammes  of  CO2."  The  minimum  excretion 
may,  therefore,  fairly  be  taken  to  be  about  seven-tenths  of 
a  cubic  foot  of  carbonic  acid  for  adult  men  and  six-tenths 
of  a  cubic  foot  for  women,  or  for  each  person  of  a  mixed 
assemblage.  Now,  it  is  evident  that  it  would  require  many 
hours  before  a  room  of,  say,  1000  cubic  feet  capacity  would 
lose  enough  oxygen  to  or  gain  sufficient  carbonic  acid  from 
a  single  adult  occupant  to  produce  even  the  slightest  appar- 
ent harmful  results  upon  him,  even  though  any  ingress  of 
fresh  air  were  absolutely  prevented;  and  yet  experience 
tells  us  that  long  before  the  lapse  of  time  necessary  to 
thus  add  sufficient  carbonic  acid  to  do  harm,  the  air  of 
such  a  room  will  become  exceedingly  foul  and  actually 
harmful  to  health.  Moreover,  carbonic-acid  gas  is  odor- 
less, while  the  air  of  inhabited,  unventilated  rooms  is 
characterized  by  a  decidedly  offensive  smell  that  remains 
for  some  time,  even  after  adequate  ventilation  has  been 
secured  and  when  chemical  tests  show  the  percentages  of 

1  Stevenson  and  Murphy,  vol  i.  p.  945. 

2  American  Journal  of  Pharmacy,  1893,  p.  561. 

3  American  Text-Book  of  Physiology,  p.  536. 


68       A  MANUAL  OF  HYGIENE  AND  SANITATION. 

carbonic  acid  to  have  been  reduced  to  nearly  the  normal. 
"  The  chemical  analyses  of  the  air  of  over-crowded  rooms, 
and  the  experiments  upon  animals  made  by  many  investi- 
gators, indicate  that  the  evil  effects  observed  are  probably 
not  due  to  the  comparatively  small  proportions  of  carbonic 
acid  usually  found  under  such  circumstances.  .  . 
The  proportion  of  increase  of  CO2  and  of  diminution  of 
oxygen  which  has  been  found  to  exist  in  badly  ventilated 
churches,  schools,  theatres,  etc.,  is  not  sufficiently  great  to 
satisfactorily  account  for  the  great  discomfort  which  such 
conditions  produce  in  many  persons,  and  there  is  no  evi- 
dence that  such  an  amount  of  change  in  the  normal  pro- 
portion of  these  gases  has  any  influence  upon  the  increase 
of  disease  and  death-rates  which  statistical  evidence  has 
shown  to  exist  among  persons  living  in  crowded  and 
unventilated  rooms. JM 

Therefore,  it  must  be  something  other  than  carbonic 
acid  that  dangerously  pollutes  the  air  of  our  dwellings  and 
necessitates  the  provision  of  some  system  of  ventilation. 
However,  with  our  present  knowledge,  we  cannot  say  that 
a  diminution  of  oxygen  and  an  increase  of  carbonic  acid 
in  the  atmosphere  which  one  breathes  habitually  does  not 
tend  to  lower  the  general  tone  and  perhaps  the  bactericidal 
powers  of  the  body,  and  thus  render  it  more  susceptible 
to  deleterious  influences;  and  there  is  some  evidence  that 
as  the  carbonic  acid  in  the  atmosphere  increases  there  is 
a  lessening  of  the  amount  of  this  gas  excreted  from  the 
body;  so  that,  on  general  principles,  it  will  be  always 
wiser  to  use  every  reasonable  means  to  maintain  the 
normal  proportion  of  the  various  gases  in  the  atmosphere. 


*  "  The  Composition  of  Expired  Air  and  its  Effect  upon  Animal  Life,"  Drs. 
Mitchell,  Billings,  and  Bergey,  No.  989,  vol.  xxix.,  Smithsonian  Contributions  to 
Knowledge. 


THE  ATMOSPHERE -AIR.  69 

Aqueous  vapor  is  another  of  the  substances  excreted  con- 
tinually from  both  the  lungs  and  the  skin,  but  it  is  obvious 
that,  in  itself,  it  cannot  be  directly  harmful  to  the  system, 
for  we  find  it  ever  present  in  all  natural  atmospheres,  and 
are  continually  replacing  its  loss  from  our  bodies  by  imbi- 
bition. The  quantity  daily  thrown  off  from  the  lungs  and 
skin  will  depend  on  the  temperature  and  humidity  of  the 
atmosphere,  the  quantity  of  air  inspired  and  water  im- 
bibed, and  many  other  factors,  but  under  ordinary  con- 
ditions the  average  excretion  will  be  from  100  to  1700 
grammes  (about  3.5  to  60  fluidounces),  though  increased 
exertion  might  cause  even  the  larger  amount  to  be  greatly 
exceeded.  It  is  accordingly  possible  that  this  large  quan- 
tity of  moisture,  tending  to  saturate  an  atmosphere  already 
humid,  might  act  indirectly  upon  the  system  by  preventing 
evaporation  from  the  skin,  and  thus  reflexly  checking  the 
excretion  of  the  waste  matters  by  the  sweat-glands,  the 
retention  of  these  wastes  in  the  system  probably  helping 
to  produce  the  depression,  headache,  and  other  symptoms 
experienced  by  those  breathing  foul  air.  It  has  been  no- 
ticed that  these  symptoms  due  to  foul  air  are  more  readily 
manifested  when  the  temperature  of  the  atmosphere  is 
much  below  or  much  above  the  usual  room  temperature  of 
65°  to  70°  F.  At  low  temperatures  it  is  easy  to  saturate 
the  air,  and  beside,  the  excreting  action  of  the  skin  is  much 
lessened  by  the  cold;  at  high  temperatures  the  humidity 
is  often  already  near  the  saturation  point,  while  the  exter- 
nal heat  tends  to  increase  the  quantity  of  water  given  off 
by  the  lungs  and  skin.  "At  high 'temperatures  the  respir- 
atory centres  are  affected  where  evaporation  from  the  skin 
and  mucous  surfaces -is  checked  by  the  air  being  saturated 
with  moisture — at  low  temperatures  the  consumption  of 
oxygen  increases,  and  the  demand  for  it  becomes  more 


70       A  MANUAL  OF  HYGIENE  AND  SANITATION. 

urgent. m  At  70°  F.  the  aqueous  vapor  from  an  adult 
body  would  completely  saturate  from  350  to  600  cubic 
feet  of  air  having  the  not  unusual  relative  humidity  of 
75  per  cent.,  while  at  80°  F.  an  equal  or  even  greater 
volume  would  doubtless  gain  its  maximum  of  moisture 
from  the  increase  of  perspiration  due  to  the  extra  heat. 

The  third  contaminant  given  to  the  air  from  human 
bodies  is  an  indefinite  volume  of  offensive  organic  matter, 
and  until  quite  recently  this  has  been  looked  upon  as  by 
far  the  most  harmful  part  of  animal  exhalations.  But 
lately  a  number  of  experiments  by  various  investigators 
have  seemed  to  indicate  that  this  organic  effluvium  is  not  so 
dangerous  as  it  has  hitherto  been  considered,  and  that  part, 
at  least,  of  the  symptoms  due  to  air  vitiated  by  respiration 
is  to  be  attributed  to  the  conditions  already  mentioned, 
viz.,  a  decrease  of  oxygen  and  an  increase  of  carbonic 
acid,  heat,  and  moisture.  It  is  also  doubtful  whether 
much,  if  any,  of  this  organic  matter  comes  from  the  lungs 
of  healthy  persons.  "  In  ordinary  quiet  respiration,  no 
bacteria,  epithelial  scales,  or  particles  of  dead  tissue  are 
contained  in  the  expired  air.  .  .  .  The  cause  of 
unpleasant,  musty  odors  in  rooms  may  in  part  be  due  to 
volatile  products  of  decomposition  from  decayed  teeth,  foul 
mouths,  or  disorders  of  the  digestive  apparatus,  and  in  part 
to  volatile  fatty  acids  given  off  with  or  produced  from  the 
excretions  of  the  skin ,  and  from  clothing  soiled  with  such 
excretions. ":!  However,  whatever  may  be  the  exact  source 
of  this  contamination,  we  know  this  concerning  it, — that  it 
is  decidedly  offensive  to  the  sense  of  smell,  that  it  is 
organic  and  nitrogenous,  yielding  ammonia,  darkening 
sulphuric  acid,  decolorizing  permanganate  of  potash,  and 

1  Drs.  Mitchell,  Billings,  and  Bergey,  loc.  cit. 

2  Ibid. 


THE  ATMOSPHERE-AIR.  71 

rendering  offensive  pure  water  through  which  vitiated  air 
has  been  drawn.  Moreover,  it  must  in  fairness  be  stated, 
that,  in  spite  of  the  later  experiments,  it  has  seemed  to  such 
careful  investigators  as  Brown-Sequard,  D'  Arson val,  Mer- 
kel,  and  others,  to  be  directly  poisonous  to  lower  animals. 
In  general,  it  is  given  off  proportionately  with  the  carbonic 
acid  from  the  body,  though  this  rule  is  not  infallible;  it  is 
apt  to  be  unevenly  distributed  throughout  the  atmosphere 
of  the  apartment,  and  is  probably,  therefore,  not  truly  gas- 
eous, but  more  like  an  impalpable  dust;  it  oxidizes  but 
slowly,  being  evident  for  some  time  after  fresh  air  has 
been  admitted  and  the  carbonic  acid  has  been  almost  re- 
duced to  the  normal,  and,  while  neither  condensed  nor  dis- 
solved in  the  aqueous  vapor  from  the  body,  it  is  especially 
attracted  and  retained  by  hygroscopic  substances,  such  as 
wool,  paper,  feathers,  etc.  Its  smell  is  generally  percep- 
tible when  the  respiratory  carbonic  acid  reaches  0.03  or 
0.04  per  cent.,  sometimes  before  this  point  is  reached, 
especially  in  sick-rooms  or  hospital  wards,  and  is  decid- 
edly offensive  when  the  total  carbonic  acid  approaches 
0. 1  per  cent. 

The  most  important  of  the  impurities  resulting  from 
the  combustion  of  coal,  the  principal  fuel  substance,  are 
soot  and  tarry  matters  (to  the  extent  of  1  per  cent,  of  the 
coal  consumed),  carbon  monoxide  and  dioxide,  aqueous 
vapor,  and  more  or  less  ammonium  sulphide,  carbon  disul- 
phide,  hydrogen  sulphide,  sulphur,  sulphur  dioxide,  and 
sulphuric  acid.  The  relative  amounts  of  the  oxides  of 
carbon — as  well  as  of  the  other  gases — will  depend  upon 
the  perfection  of  combustion;  "-but  it  has  been  calculated 
that  for  every  ton  of  coal  burnt  in  London  something  like 
three  tons  of  carbon  dioxide  are  produced,"  and  as  that 
city's  coal  consumption  is  over  30,000  tons  per  diem,  we 


72       4  MANUAL  OF  HYGIENE  AND  SANITATION. 

can  see  that  its  atmosphere  must  receive  the  enormous 
daily  contamination  of  300  tons  of  soot  and  90,000  tons 
of  carbonic  acid.  No  wonder  they  have  an  occasional  fog 
there ! 

The  combustion  products  of  wood  are  in  the  main 
simply  carbon  monoxide  and  dioxide,  and  water,  while 
those  of  coke  and  of  gas  are  practically  the  same  as  of 
coal.  From  our  heating  apparatus,  if  properly  constructed 
and  arranged,  these  products  pass  off  almost  directly  to 
the  exterior  of  our  dwellings  and  are  rapidly  dissipated,  in 
spite  of  their  excessive  volume,  for  "  diffusion  and  the 
ever-moving  air  rapidly  purify  the  atmosphere  from  car- 
bon dioxide,"  and,  in  fact,  from  the  others  also,  with  the 
exception  of  the  soot  and  tarry  products. 

Should,  however,  combustion  be  incomplete,  or  should 
the  stoves  or  other  heaters  be  imperfect,  the  gases  may 
seriously  or  even  dangerously  contaminate  the  house-air, 
the  deadly  carbon  monoxide  being  particularly  liable  to 
leak  not  only  through  the  crevices  but  actually  through 
the  heated  cast-iron  plates,  etc.,  of  stoves  and  furnaces. 
Theoretically,  a  pound  of  coal  requires  160  cubic  feet  of 
air  for  its  complete  combustion,  but  practically  from  one- 
half  to  as  much  more  must  be  supplied. 

On  the  other  hand,  practically  all  the  devices  for  arti- 
ficial illumination,  with  the  exception  of  the  incandescent 
electric  light,  give  off  their  combustion  products,  which 
are  much  the  same  as  those  from  coal,  directly  to  the  air 
which  surrounds  them,  and  this  contamination  is,  conse- 
quently, a  positive  factor  in  the  vitiation  of  in-door  air. 
"  Every  cubic  foot  of  coal-gas  yields,  on  combustion, 
roughly,  half  its  own  volume,  or  0.52  cubic  foot,  of  car- 
bon dioxide,  and  1.34  cubic  foot  of  water  vapor,"  beside 
some  little  carbon  monoxide  when  ordinary  burners  are 


THE  ATMOSPHERE— AIR. 


73 


used.  "  Speaking  generally,  it  may  be  said  that  each  cubic 
foot  of  gas  burnt  per  hour  from  the  ordinary  burners  viti- 
ates as  much  air  as  would  be  rendered  impure  by  the  res- 
piration of  an  individual;  it,  at  the  same  time,  will  raise 
the  temperature  of  31,290  cubic  feet  of  air  1°  F.,  and 
yields  217  calories  (a  kilogramme  of  water  heated  1° 
C.)  or  860  British  heat-units  (a  pound  of  water  heated 
1°  F.)."1 

The  following  table2  will  indicate  the  influence  of  various 
lighting  agents  with  respect  to  the  condition  of  the  room- 
air: 


^8 

Sg 
I8 

fi 

Oxygen 
removed. 

CO2  pro- 
duced. 

Moisture 
produced. 

•6 

IIP* 

111  III 

gop.   £0>8S 

Cu.ft. 

Cu.ft. 

Cu.ft 

Tallow  candles  . 

2200  grains 

16 

10.7 

7.3 

8.2 

1400      12.0 

Sperm  candles   . 

1740 

16 

9.6 

6.5 

6.5 

1137 

11.0 

Paraffin  oil  lamp 

992       " 

16 

6.2 

4.5 

3.5 

1030 

7.5 

Kerosene  oil  lamp     . 

909       «  : 

16 

5.9 

4.1 

3.3 

1030 

7.0 

1 

Coal  gas,  No.  5,   batwing 

5.5  cu.  ft. 

16 

6.5 

28 

7.3 

1194 

5.0 

burner. 

Coal  gas,  Argand  burner  . 

4.8   "     " 

16 

5.8 

2.6 

6.4 

1240 

4.3 

Coal     gas,     regeneration 

3.2   "     " 

-32 

. 

3.6 

1.7 

42 

760 

2.8 

(Siemens)  burner. 

Coal  gas  (Welsbach  incan-       35"    " 
descent). 

50 

4.1 

1.8 

4.7 

763       3.0 

Electric  incandescent  light 

0.3  lb  coal 

16 

0.0 

0.0 

0.0 

37 

0.0 

From  this  table  it  will  be  learned  that  the  incandescent 
light  is  the  most  satisfactory  from  a  hygienic  point  of  view, 
and  there  is  no  doubt  that  its  very  general  introduction  of 
late  has  done  much  toward  removing  a  constant  source  of 
vitiation,  especially  in  those  rooms  of  buildings  which 
require  much  artificial  light,  and  are  at  the  same  time 


Notter  and  Firth :  Treatise  on  Hygiene,  p.  140. 


2  Ibid.,  p.  141. 


74 


MANUAL  OF  HYGIENE  AND  SANITATION. 


difficult  to  ventilate.  It  is  said  that  in  a  large  bank  in 
London,  in  which  several  hundred  persons  are  employed, 
the  absences  on  account  of  illness  have  been  so  far  reduced, 
apparently  by  the  introduction  of  the  incandescent  electric 
light,  that  the  extra  labor  gained  has  more  than  paid  for 


FIG.  12. 


Chimney. 


Shade  Support. 


Mantle. 
Mantle  Support. 

Chimney  Support. 
Gauze  Tip. 

Gas  Spreader. 
Corrugated  Cap. 

antle  Carrier. 
Centre  Tube. 

Bobesche  Support. 
Gallery. 
Bunsen  Tube. 

Air  Shutter. 


.Adjustable  Check. 
Welsbach  light. 

the  increased  cost  of  lighting.  The  electric  arc  light  is 
said  to  form  nitric  acid;  but  even  so,  its  effects  are  not  so 
harmful  as  those  of  the  ordinary  gas-burner,  or  lamp,  or 
candle.  Next  to  the  incandescent  electric  light  in  impor- 
tance are  the  Welsbach  and  Siemens  gaslights;  but  of 


THE  ATMOSPHERE-AIR.  75 

these  the  latter  has  not  the  illuminating  power,  nor  is  it  so 
fitted  for  house  use  as  is  the  former.  The  Welsbach  light 
makes  use  of  the  Bunsen  flame  (in  which,  by  the  way,  the 
carbon  of  the  gaseous  fuel  is  completely  consumed  and 
converted  into  carbonic  acid)  to  render  incandescent  a 
non-combustible  mantle  or  network,  made  of  the  salts  of 
certain  rare  earths  which  have  the  property  of  becoming 
intensely  luminous  when  sufficiently  heated.  It  gives  a 
very  white  light  of  great  illuminating  and  considerable 
actinic  power,  and  of  practically  unvarying  intensity.  In 
fact,  this  quality  of  steadiness,  in  which  it  surpasses  even 
the  incandescent  electric  light,  is  by  no  means  the  least  of 
its  hygienic  advantages,  since  such  steadiness  is  an  impor- 
tant factor  in  the  conservation  of  the  eyesight. 

Sewer-Gas  and  Soil- Air.  What  is  commonly  called 
sewer-gas  is  but  a  mixture  of  a  number  of  gases,  such 
as  carbonic  acid,  carburetted  hydrogen,  ammonium  and 
hydrogen  sulphide,  nitrogen,  etc.,  together  with  a  consider- 
able amount  of  fetid  organic  matters,  the  volatile  or  semi- 
volatile  products  of  animal  and  vegetable  decomposition, 
varying  according  to  the  condition  of  the  sewer,  the  kind  of 
matter  received  therein,  the  amount  of  surplus  water,  etc. 
The  air  from  a  closed  cesspool  may  be  extremely  foul  and 
poisonous,  so  much  so  that  the  emanations  have  not  infre- 
quently brought  death  to  those  who  inhaled  them  in  full 
concentration;  on  the  other  hand,  the  atmosphere  of  a  prop- 
erly constructed  and  well-flushed  sewer  may  be  almost  as 
pure  as  that  above  the  surface.  Bacteria  are  present  in 
varying  numbers,  with  always  the  possibility  of  some  of 
them  being  the  germs  of  specific  diseases.  But  fresh  sewage 
is  not  so  likely  to  contaminate  the  air  above  it  with  these 
microbes  as  that  in  which  decomposition  has  begun,  since 
Frankland  has  shown  that  solid  or  liquid  particles  are  not 


76       A  MANUAL  OF  HYGIENE  AND  SANITATION. 

liable  to  be  scattered  into  the  air  by  any  disturbance  the 
sewage  is  likely  to  be  subjected  to  until  gases  of  decom- 
position are  produced.  The  bursting  of  bubbles  of  the 
gas  on  the  surface  may  then  throw  the  bacteria  into  the 
sewer-air.  It  has  also  been  shown  that  "  bacteria  can 
undoubtedly  grow  up  the  sides  or  walls  of  damp  nutrient 
sewers,  and  if  these  latter  become  at  all  dry,  air  currents 
readily  detach  and  disperse  them." 

Another  class  of  impurities  that  may  at  times  be  found 
in  the  air  of  dwellings  are  those  coming  from  the  soil  and 
soil-air.  The  soil,  in  hygiene,  refers  to  all  that  portion  of 
the  earth's  crust  that  can  in  any  way  affect  the  health. 
All  soils  contain  more  or  less  air — soft  sandstones  from 
20  to  40  per  cent.,  loose  sands  from  40  to  50  per  cent., 
and  loose  soils  often  many  times  their  actual  volume 
of  air. 

As  the  soil  is  the  recipient  of  most  of  the  solid  and 
liquid  waste  of  all  animal  and  vegetable  life,  and  as  the 
myriads  of  saprophytic  bacteria  that  inhabit  its  upper 
strata  are  constantly  working  to  convert  this  dead  organic 
matter  into  simpler  compounds  suited  to  the  nourishment 
of  plant-life,  the  soil-air,  taking  the  atmosphere  above  as 
a  standard,  will  usually  be  far  from  pure.  It  is  rich  in 
carbonic  acid  and  in  organic  vapors  and  gases,  while  the 
proportion  of  oxygen  seems  to  be  always  less  than  that 
of  the  air  above-ground.  Moreover,  the  carbonic  acid 
increases  and  the  oxygen  decreases  the  deeper  below  the 
surface  the  sample  is  taken.  As  much  of  the  carbonic 
acid  evidently  is  derived  from  the  organic  pollutions,  it 
might  be  supposed  that  this  gas  could  be  taken  as  an  index 
of  the  degree  of  the  latter,  and  so  it  might  if  other  con- 
ditions, such  as  permeability  of  soil,  rate  of  circulation, 
etc.,  were  always  the  same.  But  they  are  not,  and  so  the 


THE  ATMOSPHERE— AIR.  77 

composition  of  the  soil-air  is  practically  not  the  same  for 
any  two  places,  nor  for  the  same  place  at  different  times. 
It  is  constantly  in  circulation,  even  to  a  considerable 
depth,  but  there  is  a  hinderance  to  its  free  movement  and 
diffusibility,  and  this,  together  with  the  great  variation  in 
the  distribution  of  oxidizable  and  other  contaminating 
matters,  causes  the  variations  in  its  composition.  The 
carbonic  acid,  therefore,  cannot  be  taken  as  an  index  of 
the  relative  purity.  Owing  to  evaporation  from  the 
ground- water,  the  soil- air  is  always  quite  humid,  and, 
according  to  some  writers,  may  also  be  laden  with  bacteria 
and  other  light  substances  lifted  up  by  the  ascensional 
powers  of  evaporation. 

The  forces  that  maintain  the  circulation  of  the  ground- 
air  are  the  wind,  the  daily  change  of  surface  temperature, 
the  fall  of  rain,  and,  especially  in  winter,  the  local  and 
artificial  conditions  of  civilization.  A  very  slight  wind 
will  drive  the  air  through  the  soil  for  long  distances,  the 
rise  and  fall  of  the  ground-water  has  its  obvious  effect, 
and  the  movement  due  to  even  slight  changes  of  tempera- 
ture is  likely  to  be  quite  extensive  and  positive. 

As  sewage,  house-wastes,  and  dirt  of  all  kinds  are  par- 
ticularly liable  to  contaminate  the  soil  about  any  used 
dwelling,  the  air  of  that  soil  will  be  more  than  likely  to 
be  impure,  and  care  must  be  taken  that  it  is  not  drawn  up 
into  the  house.  This  is  especially  apt  to  happen  in  cold 
weather  when  the  house  fires  are  lighted  and  the  indoor 
air  is  thus  made  much  warmer  than  that  outside,  the 
tendency  then  being  for  the  soil-air  to  pass,  if  possible, 
through  the  cellar  walls  and  floors.  These  should  be 
made  as  near  air-tight  as  possible,  and  special  attention 
should  be  given  to  the  space  underneath  and  about  the 
furnaces.  As  an  instance  of  the  importance  of  these  pre- 


78       A  MANUAL  OF  HYGIENE  AND  S ANITA  TION. 

cautions,  Dr.  Hime1  gives  an  account  of  the  fatal  poison- 
ing of  four  persons.  Sufficient  illuminating  (coal)  gas  was 
drawn  through  fifteen  feet  of  soil  and  the  foundation  walls 
of  the  dwelling  from  a  broken  pipe,  although  there  were 
only  eight  or  ten  inches  of  tramped  earth  above  the  latter 
and  the  only  aspirating  force  was  the  difference  of  temper- 
ature within  and  without  the  house. 

There  is  no  direct  evidence  that  the  emanations  from 
bone-yards,  soap-factories,  garbage-incinerators,  etc.,  are 
really  harmful  to  health,  but  they  may  be  very  decided 
nuisances  to  those  living  near  by,  and  all  such  places 
should  be  properly  controlled  by  the  proper  sanitary 
authorities. 

The  atmosphere  of  mines  and  other  excavations  is  sub- 
ject to  contamination  by  the  excess  of  carbonic  acid  in  the 
soil-air,  by  gases  from  fissures  in  the  rock  and  from  blast- 
ing agents,  and  by  the  products  of  respiration  from  men 
and  animals  working  in  the  mines,  etc.  The  air  in  the 
holds  of  ships  is  also  likely  to  be  foul,  owing  to  the  diffi- 
culty of  changing  it  sufficiently  often,  and  frequently  also 
to  the  insanitary  character  of  the  cargoes.  In  such  cases 
proper  ventilation  should  be  secured  by  all  means  avail- 
able, and  special  care  taken  that  the  impure  air  does  not 
affect  passengers  or  crew. 

Diseases  Caused  by  Impure  Air.  As  a  rule,  the 
human  system  has  the  power  of  accommodating  itself, 
through  habit,  to  withstand  influences  which,  in  one  unac- 
customed to  them,  would  soon  produce  serious  results.  But 
in  spite  of  this,  if  the  body  be  exposed  for  any  consider- 
able length  of  time  to  conditions  of  impurity  or  deteriora- 
tion in  its  supply  of  air,  water,  or  food,  such  conditions 

1  Stevenson  and  Murphy  :  Treatise  on  Hygiene,  vol.  i.  p.  949. 


THE  ATMOSPHERE— AIR.  79 

will  always  tend  to  undermine  health  and  increase  the 
susceptibility  to  disease,  even  though  they  cause  no  more 
serious  results.  ' '  Statistical  inquiries  on  mortality  prove 
beyond  a  doubt  that  of  the  causes  of  death  which  are 
usually  in  action,  impurity  of  the  air  is  most  important. 
No  one  who  has  paid  any  attention  to  the  condition  of 
health,  and  the  recovery  from  disease  of  those  persons 
who  fall  under  his  observation,  can  doubt  that  impurity 
of  the  air  marvellously  affects  the  first,  and  influences,  and 
sometimes  even  regulates,  the  second.  .  .  .  The  air 
may  affect  health  by  variations  in  the  amount  or  condi- 
tions of  its  normal  constituents,  by  differences  in  physical 
properties,  or  by  the  presence  of  impurities.  While  the 
immense  effect  of  impure  air  cannot  be  for  a  moment 
doubted,  it  is  not  always  easy  to  assign  to  each  impurity 
its  definite  action.  The  evidences  of  injury  to  health 
from  impure  air  are  found  in  a  larger  proportion  of  ill 
health — L  e.,  of  days  lost  from  sickness  in  the  year — than 
under  other  circumstances;  an  increase  in  the  severity  of 
many  diseases,  which,  though  not  caused,  are  influenced  by 
impure  air,  and  a  higher  rate  of  mortality,  especially 
among  children,  whose  delicate  frames  always  give  us  the 
best  test  of  the  effect  of  food  and  air."1 

The  definitely  marked  diseases  caused  by  the  solid  im- 
purities in  the  atmosphere  are  almost  all  such  as  affect 
the  respiratory  passages  and  organs,  with  the  possible 
exception  of  those  engendered  by  specific  bacteria  and 
other  minute  organisms.  Much,  therefore,  depends  upon 
the  physical  character  of  the  /dust  and  solid  impurities. 
Soft  particles  and  those  with  edges  smooth  and  rounded, 
like  soot  and  coal-dust,  may  apparently  do  nothing  more 

1  Stevenson  and  Murphy :  vol.  i.  pp.  121  and  122. 


80      A  MANUAL  OF  HYGIENE  AND  SANITATION. 

than  clog  up  the  air  vesicles  and  finer  bronchial  tubes,  and 
in  this  way  diminish  the  area  of  lung  tissue  exposed  to 
the  inspired  air,  although  it  is  questionable  whether  any 
foreign  matter  in  the  lungs  does  not  cause  more  or  less 
actual  irritation.  With  most  of  us,  however,  such  impuri- 
ties are  of  little  account  if  pains  be  taken  to  develop  the 
full  respiratory  capacity  of  the  chest;  but  where  the  air 
is  heavily  charged  with  such  dust,  it  has  a  real  effect  upon 
health  and  duration  of  life.  In  1862  Sir  John  Simon 
stated  that  with  one  exception  "  the  300,000  (coal)  miners 
of  England  and  Wales  break  down  as  a  class  prematurely 
from  bronchitis  and  pneumonia,  caused  by  the  atmosphere 
in  which  they  live.  The  exception  is  important.  The 
colliers  of  Durham  and  Northumberland,  where  the  mines 
are  well  ventilated,  do  not  appear  to  suffer  from  an  excess 
of  pulmonary  diseases,  or  do  so  in  a  slight  degree  only/7 
Happily,  since  this  was  written  satisfactory  ventilation 
systems  have  been  placed  in  most  of  the  collieries  of  Eng- 
and,  and  the  condition  of  the  miners  correspondingly  im- 
proved; but  coal  miners  are  still,  as  a  class,  particularly 
liable  to  bronchitis,  pneumonia,  asthma,  emphysema,  and 
fibrosis  (fibroid  phthisis),  though  they  seem  to  be  but 
slightly  subject  to  tuberculosis  of  the  lungs  or  other 
organs. 

On  the  other  hand,  if  the  particles  of  dust  in  the  air  are 
hard,  angular,  and  sharp,  the  lung-tissues  are  readily  lacer- 
ated, inflammatory  processes  are  quickly  set  up,  and  the 
opportunity  for  the  inoculation  of  tubercle  bacilli  and  other 
disease-germs  is  very  great.  The  mortality  from  tuber- 
cular phthisis  among  metal  miners,  needle-cutters,  steel- 
and  tool-grinders,  cotton-spinners,  etc.,  is  remarkable; 
though  they  are  also  especially  subject  to  asthma  and 
emphysema.  Among  Cornish  tin  miners,  68  per  cent,  of 


THE  ATMOSPHERE-AIR.  81 

all  sick  are  consumptive;  of  needle-makers,  over  60  per 
cent.;  of  flint-  and  glass-cutters  and  polishers,  and  of 
grindstone  makers,  from  80  to  90  per  cent.,  etc.  It  is 
said  that  a  mixture  of  minerals  and  metallic  dust  seems 
to  be  more  harmful  than  metallic  dust  alone,  perhaps 
because  of  the  increased  clogging  of  the  air-vesicles  by  the 
mineral  matter. 

Likewise,  with  other  occupations  where  there  is  much 
irritative  dust  floating  in  the  air,  the  effect  upon  the 
health  of  the  worker  is  marked,  and  we  will  find  lung 
troubles  prevalent  and  many  sick  and  dying  from  phthisis, 
as,  for  instance,  among  cotton-spinners,  flax-  and  hemp- 
dressers,  pottery-makers,  etc.  Bad  ventilation,  accumula- 
tions of  noxious  gases,  improper  habits,  insufficient  dis- 
infection of  sputa,  and  often  the  excessive  humidity  of 
the  air  necessary  in  some  of  these  pursuits,  doubtless  have 
something  to  do  with  the  high  sick-  and  death-rates,  but 
withal,  the  marked  effect  of  the  solid  atmospheric  impuri- 
ties cannot  be  denied.  % 

Again,  workers  in  poisonous  metals,  compounds,  or 
gases,  such  as  paintmakers  and  painters,  type-setters, 
gilders  (using  mercury),  brass-founders,  and  coppersmiths, 
etc.,  are  subject  to  the  respective  poisons  and  the  symptoms 
produced  by  them,  with  a  correspondingly  increased  mor- 
tality. 

Among  the  diseases  that  may  be  caused  by  the  inhala- 
tion or  swallowing  of  specific  micro-organisms  floating  in 
the  atmosphere  are  erysipelas,  measles,  scarlet-fever,  diph- 
theria, whooping-cough,  infectious  pneumonia,  phthisis  and 
other  forms  of  tuberculosis,  and  very  probably  epidemic 
influenza;  and,  although  the  germs  of  cholera,  typhoid 
fever,  and  yellow  fever  are  usually  carried  by  the  drink- 
ing-water or  food,  they  do  sometimes  find  their  way  into 

6 


82      A  MANUAL  OF  HYGIENE  AND  SANITATION. 

the  system  from  a  contaminated  atmosphere.  Malaria 
also  is  now  practically  proven  to  be  due  to  a  minute 
organism,  which,  though  not  one  of  the  bacteria,  and 
though  usually  introduced  by  the  mouth  with  the  drink- 
ing water,  is  undoubtedly  often  present  in  the  air  of  mala- 
rial districts,  and  may  be  carried  long  distances  thence  by 
the  winds. 

Lastly,  the  spores  of  certain  fungi,  which  have  been 
found  in  the  air  of  hospitals  and  elsewhere,  are  known  to 
cause  skin  diseases,  such  as  the  tineas  and  favus  in  men; 
and  it  is  almost  as  certain  that  the  irritating  or  poisonous 
pollen  of  certain  grasses  and  other  plants  have  much  to 
do  with  the  causation  or  aggravation  of  such  maladies  as 
hay-  and  rose-fever. 

From  what  has  already  been  said,  it  will  be  surmised 
that  it  is  scarcely  possible,  at  present,  to  specify  the  exact 
effect  upon  the  health  of  each  of  the  impurities  given  to 
the  air  by  the  human  body,  and  that  the  symptoms  ob- 
served to  be  due  to  air  thus  vitiated  are  very  probably  an 
evidence  of  the  combined  action  of  these  factors  rather  than 
of  any  one  of  them  singly.  However,  the  writer  feels  that 
the  headache  and  oppression  so  commonly  experienced  are 
often  fairly  attributable  to  the  increase  in  the  temperature 
and  humidity;  that  the  disturbed  nutrition  and  febrile 
condition,  lasting  for  hours  and  sometimes  days  after 
exposure  to  air  thus  vitiated,  are  either  effects  of  the 
organic  matter  acting  as  a  poisonous  waste  when  taken 
into  the  system,  or  results  of  the  suppression  of  cutaneous 
excretion  dependent  upon  the  high  content  of  moisture  in 
the  air;  and  that  the  respiratory  carbonic  acid  in  itself 
can  but  rarely  have  much  influence  upon  comfort  or  health. 

If  the  respiratory  and  cutaneous  vitiation  be  sufficient  to 
produce  any  acute  effects,  the  immediate  symptoms  will  be 


THE  ATMOSPHERE— AIR.  83 

a  discomfort  and  sense  of  oppression,  followed  by  headache 
and  not  rarely  nausea  and  a  rather  decided  rise  of  tem- 
perature, all  three  of  which  may  last  for  some  time,  even 
after  going  into  perfectly  pure  air.  Those  who  habitually 
live  in  such  an  atmosphere  are  almost  uniformly  languid, 
pallid,  and  anaemic,  subject  to  headaches,  nausea,  and  loss 
of  appetite,  and  often  to  skin  eruptions  and  disorders,  and 
are  undoubtedly  markedly  predisposed  to  phthisis,  pneu- 
monia, bronchitis,  scrofula,  rachitis,  etc.  Moreover, 
such  an  atmosphere  apparently  favors  the  rapid  spread, 
increases  the  severity  of  and  retards  the  convalescence 
from  such  diseases  as  diphtheria,  scarlet  fever,  measles, 
typhus,  smallpox,  etc.  This  may  be  due  either  to  the 
accumulation  or  to  the  actual  multiplication  by  growth  of 
the  disease  germs  in  the  foul  air,  or  to  its  causing  a 
decrease  of  bodily  resistance  and  an  increase  in  predispo- 
sition to  such  maladies. 

When  the  proportion  of  impurities  is  very  great,  the 
results  may  be  very  serious  and  even  fatal,  as  in  the  well- 
known  cases  of  the  "  Black  Hole  of  Calcutta;"  of  the 
prison  in  which  300  captives  of  war  were  crowded  after 
the  battle  of  Austerlitz  (260  dying  very  soon  after  being 
placed  therein),  and  of  the  steamer  "  Londonderry,"  in 
which,  of  200  steerage  passengers  who  were  temporarily 
crowded  into  a  cabin  (18  x  11  x  7  feet)  during  a  storm, 
seventy-two  were  dead  and  others  dying  when  the  cabin 
was  opened. 

As  regards  the  influence  of  combustion-products  on 
health,  it  will  suffice  to  detail  the  symptoms  produced  by 
the  inhalation  of  the  various  gases.  It  will  be  difficult  to 
show  that  these  gases,  together  with  the  coincident  soot, 
have  any  general  effect  upon  health  when  escaping  into 
the  out-door  atmosphere,  even  when  produced  in  such 


84       -4  MANUAL  OF  HYGIENE  AND  SANITATION. 

enormous  quantities  in  cities  as  has  been  already  indicated. 
It  is  possible  that  the  sulphur  dioxide  and  other  sulphur 
gases  might  favor  or  aggravate  attacks  of  bronchitis  or 
asthma  in  those  living  in  the  vicinity  of  gas-works,  chem- 
ical factories,  etc.,  but  too  little  comes  from  ordinary 
chimneys  to  do  much,  if  any,  harm. 

In-doors  the  case  is  different,  for  the  gases  from  lights 
and  fires  become  more  and  more  concentrated  as  the  ven- 
tilation is  insufficient.  The  possible  effects  of  varying 
percentages  of  carbonic  acid  have  been  noted.  We  have 
no  evidence  of  cases  of  chronic  poisoning  by  this  gas, 
although,  as  Parkes  says  :  "  The  presence  of  a  very  large 
amount  of  CO2  in  the  air  may  lessen  its  elimination  from 
the  lungs,  and  thus  retain  the  gas  in  the  blood,  and  thus  in 
time  possibly  produce  serious  alterations  in  nutrition/' 

In  cases  of  acute  poisoning  by  this  gas — i.  e.,  where  it 
is  in  great  excess  in  the  atmosphere — there  is  an  almost 
immediate  loss  of  muscular  power,  and  the  person  may  be 
unable  to  remove  himself  from  the  place  of  danger,  while 
others  who  go  to  help  him  may  also  succumb  and  more 
than  one  be  asphyxiated.  Consequently,  volunteer  res- 
cuers should  remember  to  act  with  coolness  and  great 
rapidity,  and  always  to  provide  means  for  the  prompt 
removal  not  only  of  the  one  they  would  save,  but  of  them- 
selves. Fortunately,  when  one  who  has  been  overcome 
by  carbonic  acid  is  brought  into  an  atmosphere  of  pure 
air  before  life  is  extinct  and  is  aided  by  artificial  respira- 
tion, he  usually  recovers  rapidly  and  completely. 

Cases  of  poisoning  by  carbon  monoxide  are  much  more 
serious.  Recovery  from  its  effects  is  slow  and  uncertain, 
because  this  gas  unites  with  the  haemoglobin  of  the  red 
blood-corpuscles,  paralyzing  them,  as  it  were,  and  render- 
ing them  unable  longer  to  act  as  oxygen  carriers  to  the 


THE  ATMOSPHERE— AIR.  85 

tissues;  while  the  union  of  carbon  dioxide  with  the  blood 
is  always  an  unstable  one  and  readily  broken  as  soon  as 
an  interchange  with  a  normal  atmosphere  is  available. 
Less  than  one-half  per  cent,  of  carbon  monoxide  in  the 
air  has  caused  symptoms  of  poisoning,  and  more  than  one 
or  two  per  cent,  is  quickly  fatal  to  animals.  "  It  appears 
that  the  gas,  volume  for  volume,  completely  replaces  the 
oxygen  in  the  blood,  and  cannot  again  be  displaced  by 
oxygen,  so  that  the  person  Hies  asphyxiated;  but  Pokrow- 
sky  has  shown  that  it  may  be  gradually  converted  into 
carbonic  dioxide  and  be  got  rid  of." 

The  symptoms  of  carbonic  oxide  (monoxide)  poisoning 
are  feebleness,  oppressed  breathing,  trembling,  and  ina- 
bility to  swallow;  then  "  loss  of  consciousness,  destruc- 
tion of  reflex  action,  and  finally  paralysis  of  the  heart." 
"  Hirt  says  that  at  high  temperatures  (25°  to  32°  C.= 
77°  to  90°  F.)  it  produces  convulsions,  but  not  at  low 
temperatures  (8°  to  12°  C.=46°  to  54°  F.)."  The  blood 
and  muscles  are  made  a  brilliant  red  by  this  gas,  dark- 
ened by  carbon  dioxide.  Claude  Bernard  says  that  a 
mixture  of  these  two  gases  is  more  destructive  than  either 
separately,  probably  because  it  interferes  with  the  conver- 
sion of  the  monoxide  to  the  dioxide  in  the  blood,  as  was 
shown  by  Pokrowski. 

Illuminating  or  coal-gas — composed  of  hydrogen,  light 
and  heavy  carburetted  hydrogens,  a  little  nitrogen,  and 
carbonic  acid,  and  from  5  to  7  per  cent.,  or  even  more,  of 
the  carbon  monoxide — rapidly  causes,  when  inhaled,  gid- 
diness, headache,  nausea  and  vdmiting  (?),  confusion  of 
intellect,  loss  of  consciousness,  general  weakness  and  de- 
pression, partial  paralysis,  convulsions,  and  the  usual 
symptoms  of  asphyxia.  Mixed  in  large  proportions  with 
the  air,  death  may  ensue  comparatively  quickly,  probably 


86       ^  MANUAL  OF  HYGIENE  AND  SANITATION. 

because  of  the  large  content  of  carbon  monoxide;  and  it 
is  well  to  remember  that  the  so-called  water-gas,  now  so 
extensively  manufactured  for  fuel  purposes  and  also  for 
diluting  coal-gas,  contains  a  much  larger  percentage  of 
carbon  monoxide  (sometimes  from  30  to  40  per  cent.) 
than  the  latter,  and  that  the  symptoms  resulting  from  its 
inhalation  will  be  in  all  likelihood  more  marked,  more 
rapid,  and  more  deadly  than  with  the  undiluted  coal-gas. 

"  The  effects  of  constantly  inhaling  the  products  of  gas 
combustion  may  be  seen  in  the  case  of  workmen  whose 
shops  are  dark,  and  who  are  compelled  to  burn  gas  during 
a  large  part  of  the  day;  the  pallor,  or  even  anaemia  and 
general  want  of  tone,  which  such  men  show,  is  owing  to 
the  constant  inhalation  of  an  atmosphere  so  impure." 

Sulphurous  acid  gas  (SO2)  and  sulphuretted  hydrogen 
(HaS)  are  each  fatal  to  life,  the  latter  when  in  a  compara- 
tively concentrated  state;  but  they  are  offensive  and  irrita- 
ting to  the  senses,  and  thus  give  warning  of  their  presence, 
so  that  there  is  less  danger  of  their  causing  serious  results. 
Men  can  accustom  themselves  to  much  larger  proportions 
of  sulphuretted  hydrogen  in  the  atmosphere  than  can 
animals,  but  continued  exposure  to  it  is  liable  to  give  rise 
to  vertigo,  headaches,  slow  and  weak  pulse,  sweatings,  and 
loss  of  strength. 

When  sewer-gas  or  soil-air  escape  into  the  outer  air 
they  are  usually  soon  diluted  beyond  any  power  for  harm; 
but  if  either  gains  access  to  closed  rooms  or  unventilated 
dwellings,  its  effects  upon  the  inmates  is  depressing  and 
decidedly  bad.  In  either  case,  concentration  of  the  im- 
purities may  cause  acute  symptoms,  such  as  vomiting, 
purging,  severe  headache  and  prostration,  and  either 
soil-air  or  sewer-gas  may  at  any  time  carry  the  germs  of 
infectious  diseases.  Their  influence,  however,  is  usually 


THE  ATMOSPHERE— AIR.  87 

insidious,  owing  to  dilution  with  the  house-air,  and  the 
more  common  symptoms  will  probably  be  pallor,  languor, 
frequent  headaches,  loss  of  appetite,  diarrhoea,  impaired 
health,  and  often  chronic  anaemia.  Children  especially 
suffer  in  nutrition,  and  with  them  febrile  attacks  may  be 
frequent;  but  with  all  the  power  of  resisting  such  diseases 
as  typhoid  fever,  diphtheria,  etc.,  is  lessened  and  the  sus- 
ceptibility to  them  increased,  the  sickness  more  severe,  and 
the  convalescence  more  prolonged.  Indeed,  sewer-gas  and 
soil-air  probably  aggravate  all  diseases. 

In  this  connection  Alessi  has  shown  that  when  small 
animals,  such  as  rabbits,  rats,  and  guinea-pigs,  have  been 
exposed  to  sewer-air  for  some  days,  by  far  the  larger 
majority  when  inoculated  with  only  a  small  quantity  of  a 
slightly  virulent  typhoid  culture  contract  the  disease  and 
die,  while  almost  none  of  those  treated  similarly  in  every 
way  excepting  by  the  exposure  to  sewer-air,  succumb.  He 
also  showed  that  the  inoculations  were  more  deadly  when 
the  previous  exposure  to  the  noxious  gas  had  been  less 
than  two  weeks  than  when  it  exceeded  that  period,  indi- 
cating that  persons  accustomed  to  such  contamination  are 
not  apt  to  manifest  the  symptoms  due  to  it  so  rapidly  or 
so  seriously  as  are  those  who  experience  it  for  the  first 
time,  a  fact  well  known  to  all  observers. 

"  There  is  undoubtedly  a  poisonous  agency  at  work 
when  sewer-gas  is  inhaled,  which,  though  it  may  not 
directly  act,  yet  so  prepares  the  soil  that  the  system  is 
unable  to  resist  the  invading  organism  when  it  comes." 

1  Notter  and  Firth,  p.  159. 


CHAPTER    IV. 

VENTILATION    AND   HEATING. 

As  we  are  not  usually  able  practically  to  destroy  the 
impurities  of  the  atmosphere  as  fast  as  they  are  produced, 
we  have  recourse  to  ventilation  as  a  means  for  their  dilu- 
tion and  prompt  removal.  We  must  not  think,  however, 
that  we  do  all  that  is  necessary  if  we  only  renew  the  air 
within  our  dwellings,  for  unless  the  source  aud  supply 
from  which  we  take  that  which  is  to  replace  or  dilute  the 
vitiated  air  be  pure  and  clean,  any  system  of  ventilation 
which  we  may  adopt  will  be  of  little  value. 

External  ventilation  of  our  buildings,  streets,  and  cities 
is  of  importance,  then,  as  well  as  that  which  relates  only 
to  the  interior  of  our  dwellings,  workshops,  aud  places  of 
assembly.  Numerous  investigations  and  statistics,  both 
here  and  abroad,  show  that  "  the  health  of  a  town  largely 
depends  upon  the  width  of  the  streets,  the  general  height 
of  the  buildings,  and  the  amount  of  yard  space  at  the  rear 
of  each  which  separates  it  from  its  opposite  neighbor/7 
It  is  also  hard  to  overestimate  the  value  of  wide  streets, 
numerous  diagonal  ones,  and  frequent  parks  or  open  spaces, 
especially  in  the  most  thickly  inhabited  portions  of  a  city. 
In  this  connection  I  may  refer  with  advantage  to  some 
work  of  Dr.  H.  S.  Anders,  of  Philadelphia,  in  which  he 
shows  that  "  the  number  of  deaths  from  phthisis  on  a  very 
wide  street  is  proportionately  small  compared  with  those  on 
almost  any  one  narrow  street/7  and  "  that  there  is  plainly 
and  generally  a  high  mortality  rate  from  consumption 


VENTILATION  AND  HEATING.  89 

associated  with  street  narrowness  in  not  a  small  part  of 
Philadelphia,  and  that  the  relation  between  a  high  mor- 
tality and  narrow  streets  is  a  positive  and  vital  one." 
His  statistics,  covering  a  period  of  fifteen  years,  show  that 
in  one  city  ward,  certainly  favored  as  to  location,  the  ratio 
of  deaths  from  phthisis  per  square  or  block  on  streets  over 
to  those  on  streets  under  forty  feet  in  width,  was  approxi- 
mately as  3  is  to  5. 

As  regards  internal  ventilation,  it  will  be  well  to  deter- 
mine at  the  outset  the  meaning  and  limitations  of  the  term. 
Parkes  says:  "It  will  be  desirable  to  restrict  the  term 
ventilation  to  the  removal  or  dilution,  by  a  supply  of  pure 
air,  of  the  pulmonary  and  cutaneous  exhalations  of  men, 
and  of  the  products  of  combustion  of  lights  in  ordinary 
dwellings,  to  which  must  be  added,  in  hospitals,  the  addi- 
tional effluvia  which  proceed  from  the  persons  and  dis- 
charges of  the  sick.  All  other  causes  of  impurity  of  air 
ought  to  be  excluded  by  cleanliness,  proper  removal  of 
solid  or  liquid  excreta,  and  attention  to  the  conditions  sur- 
rounding dwellings."  With  the  function  of  ventilation 
thus  limited,  it  will  not  be  necessary  to  make  provision 
for  such  an  abundant  supply  of  pure  air  as  might  other- 
wise seem  advisable.  It  is  evident,  also,  that  the  purity 
of  in-door  air  must  almost  always  be  relative  and  not 
absolute,  especially  in  a  climate  like  ours,  which,  for  a  con- 
siderable portion  of  the  year,  necessitates  the  warming  of 
the  air  and  some  consequent  economy  in  its  use. 

It  seems  strange  that  more  attention  has  not  been  given 
to  the  possibility  of  purifying  a  vitiated  atmosphere  by 
means  of  fire  rather  than  by  the  removal  or  dilution  of 
the  impurities,  especially  as  we  so  often  employ  heat  as  an 
agent  to  destroy  or  alter  the  harmful  qualities  of  other 
substances  intimately  concerned  with  our  welfare.  The 


90       ^  MANUAL  OF  HYGIENE  AND  SANITATION. 

objection  that  many  would  offer  at  first  thought  to  such  a 
plan  is  that  the  fire  would  rob  the  air  of  all  or  most  of 
its  oxygen,  but  a  little  calculation  and  consideration  will 
show  that  this  is  by  no  means  a  necessary  result,  and  that 
a  proper  apparatus  might  actually  require  but  compara- 
tively little  of  this  gas  and  give  off  but  little  carbonic  acid 
as  a  combustion  product  to  the  atmosphere.  So  far  as  the 
writer  knows,  but  one  device  on  the  market  has  this  func- 
tion professedly  embodied  in  it,  and  it  apparently  does 
what  is  claimed  for  it  in  this  respect.  The  possibilities  of 
the  suggestion  invite  further  investigation. 

To  discover  the  quantity  of  air  desirable  and  consistent 
with  the  requirements  of  good  ventilation  and  the  non- 
interference with  health,  two  factors  must  be  determined  : 
(a)  The  extent  to  which  the  air  of  a  room  is  contaminated 
in  a  given  time  by  the  impurities  it  receives,  and  (6)  the 
limit  of  permissible  impurity  beyond  which  there  will  be 
a  possible  risk  or  detriment  to  health.  In  accordance 
with  the  above  limitations  of  Parkes,  the  contaminating 
substances  will  usually  be  comparatively  few  in  number, 
but  the  same  rules  are  to  be  applied  in  the  case  of  any 
detrimental  substances  in  the  atmosphere  at  any  time,  pro- 
vided their  source  or  cause  cannot  be  directly  removed. 

Although  it  is  extremely  difficult  to  determine  quanti- 
tatively the  organic  matter  given  off  by  human  exhalation 
in  any  given  time,  the  carbonic  acid,  as  has  already  been 
stated,  is  usually  given  off  in  a  reasonably  constant  ratio 
with  it,  and  can,  therefore,  be  used  as  an  index  of  the 
amount  contaminating  the  air.  Taking  Pettenkoffer's 
figures,  viz. ,  0. 6  cubic  feet  of  carbonic  acid  per  hour  per 
head  for  a  mixed  assemblage  at  rest,  0.7  cubic  feet  for 
adult  males,  and  increasing  amounts  according  to  the 
physical  work  done,  which  have  been  substantially  con- 


VENTILATION  AND  HEATING.  91 

firmed  by  other  investigators,  we  have  the  first  factor  (a) 
of  our  problem  determined  for  all  cases  where  the  products 
of  respiration  are  the  only  contaminants. 

In  establishing  the  limit  of  permissible  impurity — the 
second  factor  (b) — it  will  naturally  be  advisable  to  require 
that  the  supply  of  air  from  without  shall  be  sufficient  not 
only  to  be  thoroughly  consistent  with  health,  but  that  there 
may  be  no  perception  of  impurity  by  the  senses,  the  air  of 
the  room  remaining  apparently  as  fresh  and  pure  as  that 
out  of  doors.  To  this  end  Dr.  de  Chaumont  made  a  large 
number  of  observations  (over  450),  and  found  that  as  long 
as  the  carbonic  acid  due  solely  to  respiratory  impurity  did 
not  exceed  0.02  per  cent.,  the  in-door  air  did  not  differ 
sensibly  from  that  without,  but  that  when  the  respiratory 
CO2  reached  0.04  per  cent.,  the  air  was  rather  "  close/7 
and  the  organic  matter  was  becoming  perceptible  to  the 
sense  of  smell.  Subsequent  investigations  have  shown 
that  as  long  as  the  respiratory  CO2  does  not  exceed  0.02 
per  cent,  it  has  no  perceptible  effect  upon  the  health  ; 
consequently,  we  may  take  this  amount  of  carbonic  acid 
over  and  above  the  amount  normally  present  at  the  time 
in  the  outer  atmosphere  as  our  limit  of  permissible  im- 
purity in  inhabited  apartments. 

Having  now  the  two  factors  of  our  problem,  it  becomes 
a  simple  matter  of  proportion  to  determine  the  amount 
of  fresh  air  to  be  supplied  to  each  individual,  provided 
there  are  no  other  sources  of  contamination.  The  equiva- 
lent of  0  02  per  cent,  is  0.0002  of  a  cubic  foot  of  carbon 
dioxide  in  each  cubic  foot  of  air.  In  a  mixed  assembly 
each  person  exhales  0.6  cubic  foot  of  carbon  dioxide  per 
hour.  Consequently,  to  dilute  this  respiratory  CO2  prop- 

o  f{ 

erly,  each  person  will  need  — - —  or  3000  cubic  feet  of 
/J  0.0002 


92       A  MANUAL  OF  HYGIENE  AND  SANITATION. 

fresh  air  per  hour.  If  the  individuals  are  all  adult  males, 
or  if  they  are  working,  there  must  be  a  corresponding 
increase  in  the  air  supplied,  running  up  to  6000  or  even 
9000  cubic  feet  or  more  per  head  in  certain  laborious  occu- 
pations. This  is  the  theoretical  amount  necessary  for  good 
ventilation,  but  in  practice  we  find  that  we  can  get  along 
with  safety  and  comfort  with  somewhat  less  fresh  air,  be- 
cause some  of  the  bodily  impurities  are  at  once  carried  away 
and  out  of  the  room  by  the  draughts  through  the  exits,  or 
through  cracks  and  crevices  in  the  walls  and  ceiling  which 
act  as  exits,  and  the  incoming  air  does  not,  therefore,  have 
to  mix  with  and  dilute  that  portion  of  the  impurities  that 
is  so  immediately  removed.  In  other  words,  if  10  per  cent, 
of  the  vitiation  is  thus  directly  removed,  10  per  cent,  less 
of  pure  air  is  needed  to  dilute  the  remaining  contaminants 
to  the  limit  of  permissible  impurity;  but  as  the  quantity 
and  the  consequent  velocity  of  the  incoming  or  of  the  out- 
going air  diminishes,  less  and  less  of  the  impurities  are 
thus  directly  removed,  and  experience  teaches  that  almost 
the  full  theoretical  amount  of  fresh  air  is  needed  in  prac- 
tice to  secure  satisfactory  results. 

Provision  must  also  be  made  for  sufficiently  diluting 
the  impurities  from  other  sources  of  vitiation  whenever 
they  are  present.  Although  combustion  products  are  not 
usually  as  dangerous  as  impurities^  from  the  human  body, 
and  though  they  are  generally  massed  near  the  top  of  the 
room,  we  should  provide  at  least  1800  cubic  feet  of  air  for 
each  cubic  foot  of  gas  burned,  and  ten  times  as  much  for 
each  pound  of  oil  consumed. 

In  sick-rooms  and  hospitals  an  exception  must  also  be 
taken  to  the  equation  in  which  0.02  per  cent,  of  carbonic 
acid  is  taken  as  the  permissible  respiratory  impurity,  for 
it  is  found  that  the  organic  matter  exhaled  from  the  sick 


VENTILATION  AND  HEATING.  93 

is  much  more  offensive  than  that  from  the  healthy,  and  is 
noticeable  to  the  senses  when  the  respiratory  CO2  is  much 
below  0.02  per  cent.  So,  one-fourth  or  more  of  fresh  air 
at  least  must  be  added  to  the  usual  amount  to  be  supplied 
to  the  healthy,  and  the  rule  is  to  give  the  sick  as  much 
as  possible,  provided  it  be  properly  warmed  and  dis- 
tributed. 

The  use  of  the  following  formula  will  often  be  advisable 

in  solving  problems  relating  to  ventilation,  viz.  :  -  =  d, 

where  e  represents  the  amount  of  carbonic  acid  exhaled  in 
the  given  time,  r  the  respiratory  CO2  in  parts  per  cubic  foot, 
and  d  the  delivery  or  volume  of  fresh  air  in  cubic  feet.  Ex- 
ample: What  will  be  the  respiratory  impurity  in  the  air  of 
a  room  of  3000  cubic  feet  capacity  which  has  been  occupied 
by  three  men  for  two  hours,  supposing  that  there  has  been 
an  ingress  of  9000  cubic  feet  of  fresh  air  in  that  time  ? 
Here  e  =  0.7  X  3  X  2  =  4.2,  and  d  =  3000  +  9000  = 

12,000.     ^  =  12,000  :  =  r  =  0.00035  =  0.035 


per  cent.  CO2. 

Before  considering  the  means  by  which  a  sufficient  quan- 
tity of  pure  air  may  be  supplied  to  buildings  and  apart- 
ments, it  will  be  well  to  note  the  following  restrictions  as 
to  the  size  and  height  of  the  rooms.  If  a  room  be  too 
small,  the  air  therein  will  have  to  be  changed  often,  the 
velocity  at  the  inlets  will  be  increased,  uncomfortable 
draughts  will  be  created,  and  the  air  will  not  diffuse  itself 
so  thoroughly  throughout  the  room.  Experience  shows 
that  even  when  the  air  is  properly  warmed  it  cannot  be 
changed  much  oftener  than  three  times  an  hour  without 
discomfort  to  the  occupants  of  the  room,  unless  the  venti- 
lating apparatus  be  very  perfect  in  its  workings,  and, 


94      A  MANUAL  OF  HYGIENE  AND  SANITATION. 

therefore,  expensive.  Consequently,  as  we  take  3000 
cubic  feet  of  fresh  air  to  be  the  average  amount  required 
per  person  per  hour,  the  cubic  space  per  individual  should 
be  at  least  1000  cubic  feet,  with  a  corresponding  increase 
where  the  occupants  are  all  adult  males,  are  all  at  work, 
or  are  in  hospitals. 

Again,  it  must  be  remembered  that  the  difficulty  of 
securing  equable  heating  and  ventilation  increases  with 
the  height  of  the  room  above  a  certain  limit,  and  that 
with  the  sick  especially  a  certain  amount  of  floor-space  is 
necessary,  both  for  the  separation  of  patients  and  conven- 
ience of  attendance.  Ten  or  twelve  feet  will  usually  be 
found  to  be  the  safe  limit  of  height  for  all  apartments 
intended  for  continuous  rather  than  temporary  occupation, 
and,  consequently,  there  should  be  a  minimum  allowance 
of  from  85  to  100  or  more  square  feet  of  floor-space 
per  head,  and  an  increase  even  upon  this  in  workshops, 
hospitals,  etc.  However,  there  is  no  objection  to  high 
ceilings  if  you  are  not  limited  as  to  floor-space,  pure  air 
supply,  and  heat;  and  they  may  even  be  advisable  in 
rooms  where  many  lights  are  to  be  burned.  Again,  these 
restrictions  regarding  cubic  and  floor-space  do  not  neces- 
sarily apply  to  such  buildings  as  churches,  theatres,  etc., 
which  are  occupied  for  only  a  comparatively  limited  time, 
which  can  be  thoroughly  flushed  out  after  use,  and  in 
which  it  is  evidently  impracticable  to  allot  to  each  person 
the  above  floor  area.  Yet  pains  must  be  taken  in  such 
assemblies  to  keep  the  atmosphere  pure  by  whatever  means 
are  necessary;  while  for  school-rooms  and  the  like  there 
must  be  extreme  care  that  the  pupils  are  not  overcrowded, 
and  that  they  have  a  full  supply  of  properly  warmed  air. 

Any  correct  system  of  ventilation,  in  addition  to  the 
above  considerations,  must  take  into  account  the  source  of 


VENTILATION  AND  HEATING.  95 

the  air  supplied,  the  distribution,  and  the  heating  or  cool- 
ing of  the  air  when  necessary. 

The  air  supplied  to  any  house  should  be  taken  from 
well  above  the  level  of  the  ground,  where  it  is  free  from 
contamination  and  is  constantly  changing,  and  not  from 
cellars  or  closed  areas,  where  the  atmosphere  is  stagnant 
and  full  of  impurities.  The  conduits  leading  to  the  heat- 
ing or  ventilating  apparatus  should  also  be  so  arranged 
that  they  may  be  frequently  and  readily  cleaned;  it  is  well 
to  have  them  covered  with  gratings  to  prevent  objects 
being  thrust  into  them,  and,  in  extreme  cases,  it  may  even 
be  advisable  to  filter  the  air  through  coarse  cloth  or  fine 
wire  gauze  to  free  it  from  dust  and  other  impurities.  In  the 
mechanical  system  of  ventilation  adopted  in  the  chemical 
laboratory  of  University  College,  Dundee,  the  air  is  filtered 
by  being  passed  through  jute  cloth  (light  Hessian)  stretched 
on  frames  seventeen  feet  long  by  four  feet  wide.  In  this 
case  the  presence  of  the  screen  actually  increased  the  de- 
livery of  the  air  by  nearly  10  per  cent.,  probably  by  pre- 
venting eddies.  The  screens  collected  two  and  one-half 
pounds  of  dirt  in  seven  weeks.  They  last  about  a  year, 
and  the  cost  is  about  2d  (four  cents)  a  yard.1 

The  air  may  be  kept  in  motion  and  efficient  ventilation 
produced  (1)  by  those  forces  continually  acting  in  nature, 
producing  natural  ventilation,  and  (2)  by  these  in  combina- 
tion with  other  forces  set  in  action  by  man,  giving  artificial 
ventilation.  The  three  main  forces  of  natural  ventilation 
are  diffusion,  the  winds,  and  the  difference  in  weight  of 
volumes  of  air  of  different  temperatures. 

Diffusion  is  constantly  taking  place  between  all  the  gas- 
eous constituents  and  impurities  of  the  air,  and  even  goes 

1  Stevenson  and  Murphy,  vol.  i.  p.  51. 


96       A  MANUAL  OF  HYGIENE  AND  SANITATION. 

on  through  brick  and  stone  walls,  but  is  insufficient  in 
itself  to  keep  the  air  pure,  though  it  does  much  to  further 
this.  Moreover,  as  suspended  matters  are  solid,  not  gas- 
eous, they  are  not  changed  or  removed  by  it. 

However,  the  action  of  this  force  should  not  be  ignored 
in  our  calculations  as  being  insignificant,  for  it  is  not 
only  continuous,  but  it  affects  the  whole  volume  of  the 
atmosphere  in  maintaining  its  uniformity  of  composition. 
u  Roscoe  found  that  when  he  evolved  carbon  dioxide  in  a 
room  the  amount  had  decreased  one-half  from  that  cause 
(diffusion)  in  ninety  minutes."1  The  rate  of  diffusion  is 
inversely  as  the  square  roots  of  the  densities  of  the  gases 
concerned. 

Winds  are  powerful  agents  for  ventilation,  and  a  slight 
breeze  passing  through  a  room  changes  the  air  therein 
many  times  in  the  course  of  an  hour,  and  carries  out  by 
its  force  many  of  the  solid  impurities  not  affected  by  diffu- 
sion. Winds  will  pass  through  walls  of  wood,  brick,  or 
stone,  although  their  progress  is  markedly  arrested  by 
much  moisture  in  the  walls  and  by  paper  or  plaster. 
The  average  rate  of  movement  of  the  wind  is  consider- 
able, but  the  difficulties  in  the  way  of  applying  them  in 
ventilation  are  the  uncertainty  of  their  direction  and 
velocity,  the  difficulty  of  regulating  them,  and  the  fact 
that  they  may  fail  us  at  a  time  when  we  need  their  action 
most.  In  winter  they  usually  have  to  be  excluded  directly 
from  our  houses,  because  a  velocity  of  five  or  six  feet 
per  second  is  not  to  be  borne  unless  the  air  be  pre- 
viously warmed.  We  may,  however,  take  advantage  of 
the  fact  that  a  small  current  with  a  high  velocity  will  set 
in  motion  a  large  volume  of  air,  and  that  wind  blowing 

i  Notter  and  Firth,  p.  194. 


VENTILATION  AND  HEATING. 


97 


across  the  top  of  a  tube  will  cause  an  upward  movement 
of  air  in  the  tube.  This  is  one  reason  why  there  is  often 
a  draught  up  an  unusued  chimney  and  why  it  acts  as  a 
good  ventilating  outlet.  To  utilize  these  perflating  and  as- 
pirating powers  of  the  wind,  and  to  prevent  back  draughts 
down  chimneys  and  ventilating  pipes,  we  make  use  of  cowk, 
either  movable  or  fixed.  We  can  so  arrange  these  that 


FIG.  13. 


Cowl  or  ventilator' for  aspiration. 

the  force  of  the  wind  either  drives  air  into  the  house  (per- 
flation),  or  draws  air  out  of  it  (aspiration).  '  Very  good 
systems  employing  these  have  been  put  in  operation,  the 
air  being  warmed,  if  necessary,  by  passing  it  over  stoves, 
steam  coils,  etc.,  and  they  are  especially  useful  where  the 

7 


98       A  MANUAL  OF  HYGIENE  AND  SANITATION. 

inner  air  is  colder  than  that  externally,  and  where  arti- 
ficial methods  of  ventilation  dependent  upon  heat  cannot 
be  employed,  as  in  the  holds  of  ships,  deep  basements, 
etc. 

The  most  important  agent  in  natural  ventilation  is,  how- 
ever, the  movement  produced  by  variations  in  the  specific 
gravity  of  air.  Though  the  wind  might  be  included  under 
this  head,  being  produced  by  the  same  force,  the  latter 
acts  independently  of  the  wind,  especially  in  closed  build- 
ings. As  the  air  expands  when  heated,  equal  volumes  be- 
come lighter  than  they  were  hitherto  and  rise,  and  colder, 
heavier  air  pushes  in  beneath  to  occupy  the  space.  But 
in  all  inhabited  apartments  a  warming  of  the  atmosphere 
is  continually  taking  place,  not  only  by  the  lights  and 
fires,  but  also  by  the  bodies  of  the  occupants.  The 
movement  is,  therefore,  a  continual,  though  not  neces- 
sarily an  equable  one,  varying  as  it  does  with  the  tem- 
perature of  the  out-door  air  and  the  number  and  inten- 
sity of  the  heating  agents  within.  There  being  such  a 
heating  and  movement  of  the  air,  it  follows  that,  unless  a 
room  be  perfectly  air-tight,  some  of  the  apertures  will  act 
as  inlets  and  others  as  outlets,  and  the  quantity  flowing 
out  of  the  room  will  be  practically  equivalent  to  that  flow- 
ing into  it.  Therefore,  though  this  force  may  not  be  as 
powerful  or  efficient  as  strong  winds  at  certain  times,  yet 
being  more  constant,  more  readily  calculated,  and  more 
controllable,  it  is  the  one  most  to  be  considered  in  arrang- 
ing a  system  of  ventilation. 

To  determine  the  velocity  of  this  influx  or  outgo  of  air, 
we  make  use  of  the  law  that  a  fluid  passes  througli  an  open- 
ing in  a  partition  between  two  volumes  of  the  fluid  with 
the  velocity  which  a  body  would  acquire  in  falling  through 
a  height  equal  to  the  difference  in  level  of  the  fluid  on  the 


VENTILATION  AND  HEATING.  99 

two  sides  of  the  partition.  In  the  case  of  a  current  of 
air  we  substitute  for  the  difference  of  level  the  difference 
in  pressure  on  the  two  sides  of  the  partition  or  opening, 
•and  this  is  expressed  by  the  difference  in  temperature 
multiplied  by  the  difference  in  height  of  the  openings  of 
entrance  and  exit,  and  divided  by  491,  T^T  representing 
the  expansion  of  the  atmosphere  in  volume  and  lessening 
of  density  for  each  degree  (Fahrenheit)  of  rise  in  temper- 
ature. The  velocity  will,  therefore,  equal 


/ 

^ 


(diff.  in  temp.)  X  (diff.  in  height). 
~~ 


Example:  What  is  the  velocity  of  the  current  in  a  chim- 
ney 40  feet  high,  the  out-door  temperature  being  20°  F. 

and  in-doors  70°  F.?    Answer  :  V=  8  .  /5Q  x  ^  =  8  X 

\     491 
2  +,  or  about  sixteen  feet  per  second. 

In  actual  practice  use  is  made  of  a  table  derived  from 
this  formula,  or  else  the  velocity  is  determined  directly  by 
means  of  the  anemometer.  Allowance  must  be  made  for 
the  friction  of  the  air  against  the  sides  of  the  ducts  and 
against  itself,  amounting  to  from  one-fourth  to  one-half 
of  the  theoretical  delivery,  according  to  the  length,  size, 
straightness,  etc.,  of  the  inlets  and  outlets.  The  friction 
will  be  inversely  as  the  diameter  of  the  openings  and 
directly  as  the  length  of  the  tubes;  the  shape  of  the  open- 
ings also  affect  it,  and  right  angles  diminish  the  current 
one-half.  Accumulations  of  dust  and  dirt  greatly  lessen 
the  velocity. 

The  velocity  multiplied  by  the  total  area  of  the  inlets 
or  outlets,  with  a  proper  allowance  for  friction,  will  give 
the  quantity  of  air  passing  through  the  rooms  or  series  of 
rooms  in  any  given  time. 

One  of  the  most  difficult  problems  in  ventilation  is  to 


100 


MANUAL  GF  HYGIENE  AND  SANITATION. 


secure  a  uniform  distribution  of  pure  air  through  the 
rooms,  and  to  remove  the  impure  air  as  fast  as  the  pure 
is  supplied,  thus  preventing  its  mixing  with  the  latter. 
Certain  circumstances  always  make  the  question  compli- 
cated: the  size  and  number  of  inlets  and  outlets,  the  rate 
and  direction  of  motion,  and  the  forces  acting  to  produce 
it  must  always  be  subject  to  constant  change,  and  must 
thus  constantly  alter  the  result.  In  fact,  it  is  practically 
impossible  to  devise  a  plan  that  will  satisfy  all  conditions 
at  all  times,  and  the  best  that  can  be  done  will  be  to  select 
that  one  which  will  give  the  greatest  efficiency  and  most 
satisfactory  results  under  all  ordinary  circumstances. 

FIG.  14. 


Anemometer,  used  for  measuring  the  velocity  of  air-currents  directly,  a,  slide 
for  releasing  or  stopping  the  dial  hands  ;  e,  support  for  attaching  the  instrument 
to  a  staff  or  cane. 

The  force  of  diffusion  will  always  act  as  long  as  there 
is  any  communication  between  the  exterior  and  interior, 
and  no  special  attention  need  be  given  to  it.  We  cannot 
use  the  wind  continually,  for  reasons  already  given,  but 


VENTILATION  AND  HEATING.  101 

we  should  employ  it  whenever  possible  by  opening  doors 
and  windows,  on  account  of  its  great  power  for  sweeping 
out  solid  impurities  and  thoroughly  changing  the  air.  In 
cold  weather,  currents  from  windows,  etc.,  should  be 
directed  toward  the  ceiling,  so  that  they  may  be  diffused 
and  partially  warmed  before  reaching  the  inmates  of  the 
room.  Numerous  devices  have  been  suggested  for  intro- 
ducing unwarmed  out-door  air  without  discomfort,  or  for 
diffusing  it  through  the  room:  among  these  may  be  men- 
tioned perforated  bricks,  or  double-paned  windows,  valves, 
screws,  etc.  A  cheap  and  satisfactory  temporary  arrange- 
ment is  to  place  a  board  about  four  inches  wide  and  just 
as  long  as  the  width  of  the  window-sash  beneath  the  latter. 
Or,  better,  have  a  light  frame  covered  with  fine  netting 
or  wire-gauze,  four  or  five  inches  wide  made  to  fit  above 
the  upper  sash  :  the  fresh  air  from  without  can  now 
enter  freely  between  the  upper  and  lower  sash,  being  re- 
flected upward  by  the  inner  surface  of  the  glass  in  the 
upper  sash,  and  thus  mixing  with  warm  air  before  reach- 
ing the  occupants  of  the  room;  while  the  frame  at  the 
top  of  the  window  becomes  an  outlet  for  the  foul  air,  the 
interference  of  the  netting  or  gauze  preventing  too  rapid 
an  outgo  and  consequent  loss  of  heat.  But  in  a  climate 
such  as  our  own,  and  in  all  cold  countries,  special  meas- 
ures must  be  taken  during  the  greater  part  of  the  year  for 
warming  the  out-door  air  before  introducing  it  into  occu- 
pied rooms. 

Where  we  intend  to  depend  most  upon  the  third  force 
of  natural  ventilation,  viz.,,  the  movement  of  unequal 
weights  of  air,  we  must  provide  openings  for  the  entrance 
and  exit  of  air  other  than  the  windows  and  doors,  so  that 
there  will  be  a  practically  constant  movement  through  the 
rooms  in  a  given  direction,  that  we  may  be  sure  the  air  is 


102 


MANUAL  OF  HYGIENE  AND  SANITATION. 


from  a  pure  source,  and  that  we  may  get  the  utmost  ser- 
vice from  our  appliances. 

There  is  considerable  difference  of  opinion  as  to  the  best 
locations  for  inlets  and  outlets,  and  as  the  conditions  are 
necessarily  different  in  every  case,  and  as  so  many  factors 
are  to  be  considered,  it  is  difficult  to  lay  down  any  general 
rules.  It  should  be  an  aim,  however,  to  have  the  air  well 

FIG.  15. 


Currents  in  room  lighted  by  gas  and  heated  by  open  grate. 

distributed  throughout  the  room  or  rooms,  and  to  have  no 
direct  draughts  from  the  inlets  either  upon  the  occupants 
or  to  the  outlets.  It  is  the  writer's  opinion  that,  usually, 
the  outlets  should  be  located  near  the  top  of  the  room, 
owing  to  the  tendency  of  the  used  air  to  rise,  and  because, 
in  unventilated  rooms,  the  foulest  air  for  some  time  after 
its  contamination  will  be  found  nearest  the  ceiling.  The 
products  of  combustion  from  lights,  etc.,  will  also  practi- 


VENTILATION  AND  HEATING. 


103 


cally  all  be  in  the  upper  strata  of  air.  If,  however,  pro- 
vision is  or  can  be  made  for  a  constant  and  sufficiently 
strong  aspirating  force  in  the  outlet  ducts,  it  will  be  advis- 
able to  withdraw  the  used  air  near  the  floor  level  and 
below,  though  not  in  too  close  proximity  to,  the  inlet  open- 
ings, since  in  this  way  a  more  thorough  distribution  of  the 
incoming  air  and  a  greater  dispersion  of  its  contained  heat 
are  secured.  This  is  aptly  shown  in  the  illustration  depict- 

FIG.  16. 


Currents  in  room  heated  by  a  ventilating  grate. 

ing  the  currents  in  a  room  heated  by  a  ventilating  grate. 
(Fig.  16.)  This  principle  is  also  involved  in  the  well-known 
Smead  system  of  ventilation  and  heating,  which  still 
further  serves  economy  by  carrying  the  foul  air  beneath  the 
floor  of  the  room  from  which  it  is  taken,  thus  warming  the 
floor  with  what  heat  the  waste-air  yet  contains  and  gaining 
the  utmost  benefit  and  value  from  the  fuel.  (Fig.  17). 
The  location  of  the  inlets  should  depend  on  the  tempera- 


104    A  MANUAL  OF  HYGIENE  AND  SANITATION. 


ture  of  the  incoming  air;  if  it  is  cold,  it  should  be  admitted 
near  the  ceiling,  so  that  it  may  diffuse  and  be  practically 
warmed  before  reaching  the  inmates  of  the  room;  if  it  is 
warmed,  it  may  come  in  near  the  floor  or  below  the  middle 
level  of  the  room.  Where  much  fresh  air  is  required,  it 
is  better  to  have  a  number  of  inlets  and  outlets  than  one 
large  one  of  each,  as  the  distribution  is  then  more  certain. 
The  total  area  of  the  outlets  may  be  the  same  as  that  of 


FIG.  17. 


Diagram  illustrating  the  general  system  of  ventilation. 

the  inlets,  as  the  expansion  of  the  air  is  scarcely  great 
enough  to  require  a  difference.  The  outlets  should  all  be 
on  the  same  level,  else  the  highest  one  will  be  the  one  of 
greatest  discharge  and  often  the  only  one,  the  others  pos- 
sibly acting  as  inlets  and  drawing  air  from  an  impure 
source.  As  the  temperature  varies  from  time  to  time,  and 
with  it  the  current,  some  arrangement  is  needed  for  regu- 
lating the  size  of  the  openings  of  the  inlets  or  outlets  to 


VENTILA  TION  AND  HE  A  TING.  105 

suit  the  varying  conditions.  To  supply  3000  cubic  feet 
of  air  per  head  per  hour  at  a  velocity  of  five  feet  per  second 
will  require  an  inlet-opening  of  twenty-four  square  inches 
for  each  person;  but  practically  it  is  better  to  have  a  larger 
opening,  as  the  above  velocity  is  uncomfortable  unless  the 
air  be  well  warmed.  Outlet  tubes  should  always  be  pro- 
tected from  cold  and  kept  as  warm  as  possible. 

Artificial  ventilation  is  that  which  is  brought  about  by  the 
intentional  application  of  the  above  mentioned  and  other 
forces,  and  by  means  of  special  apparatus  and  devices,  in 
contradistinction  to  natural  ventilation,  which  may  act  in- 
dependently of  human  cognizance  and  intention.  It  may 
consist  in  either  extracting  air  from  or  forcing  air  into  a 
room  or  building,  or  in  both  together.  In  the  first  method 
the  object  may  be  attained  by  heating  the  air  in  the  outlet  or 
the  outlet  itself,  or  by  the  use  of  a  fan,  a  screw,  or  a  steam  or 
water-jet.  Of  the  first  of  these  the  common  house-chimney 
is  as  good  an  example  as  any.  As  long  as  there  is  a  fire  in 
a  grate  or  stove  connected  with  the  chimney  there  will 
be  a  constant  upward  current;  and  the  area  of  the  chim- 
ney's cross  section  being  known,  and  the  velocity  deter- 
mined, as  already  indicated, by  the  anemometer  or  by  calcu- 
lation, the  amount  of  air  passing  out  of  the  room  in  this 
way  may  readily  be  determined.  In  this  connection  it 
may  be  stated  that  a  chimney  may  thus  act  as  the  only 
outlet,  and  all  other  openings  into  the  room  serve  as  inlets, 
especially  when  the  fire  is  strong,  and  that  the  upward 
current  will  be  practically  equivalent  to  the  amount  of 
incoming  air.  Moreover,  the  outgoing  current  may  be  so 
strong  as  to  overtax  the  capacity  of  the  inlets,  in  which 
case  more  or  less  of  a  vacuum  will  be  formed  in  the  room 
and  down  draughts  will  probably  be  set  up  in  the  chimney  ? 
and  smoke  carried  back  into  the  room.  The  remedy  is  to 


106    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

enlarge  the  inlet  area  by  opening  a  door  or  window,  or  to 
lessen  the  draught  by  means  of  a  damper  in  the  chimney. 
On  the  other  hand,  the  inlets  may  be  so  large  and  the 
current  so  strong  that  the  air  in  the  room  cannot  be  prop- 
erly warmed,  in  which  case  the  size  of  the  outlet  should 
be  lessened  by  a  damper,  or  there  should  be  an  increase  in 
the  efficiency  of  the  heating  apparatus. 

When  we  wish  to  draw  air  from  distant  and  non-com- 
municating rooms,  the  ducts  may  be  led  into  a  chimney 
below  or  just  above  a  fire,  or,  better,  into  a  flue  or  shaft 
alongside  or  encircling  the  heated  chimney.  The  draught 
is  greater  just  above  a  fire  than  below  it,  but  conduits 
should  not  enter  near  the  top  of  a  chimney,  for  there  the 
extracting  power  is  not  so  great  and  there  is  danger  of  high 
winds  blowing  smoke  and  foul  air  back  into  the  rooms. 
Outlet  flues  should  be  alongside  chimneys  that  are  being 
constantly  used;  should  be  as  smooth  as  possible  interi- 
orly, and  should  be  as  high  as  the  adjoining  chimney  to 
avoid  down  draughts.  The  openings  from  the  rooms  into 
these  ducts  should  be  as  near  the  ceiling  as  possible,  to  get 
the  benefit  of  the  high  temperature  of  the  upper  strata  of 
air,  unless,  as  previously  indicated,  there  is  certainty  of  the 
extracting  force  being  constant  and  sufficiently  strong, 
when  the  air  may  be  taken  from  a  lower  level. 

In  hospitals  and  other  places  where  a  constant  and  inde- 
pendent supply  of  heat  can  be  afforded,  extraction  shafts 
apart  from  chimneys  may  be  used.  These  extraction  shafts 
may  be  heated  by  fires,  steam  pipes,  or  steam  jets  at  the 
bottom,  or  by  steam  or  hot-water  pipes  coiled  around  the 
sides.  Some  system  like  this  is  used  in  mines,  where  large 
quantities  of  air  must  be  extracted.  There  is  an  entrance 
and  an  extraction  shaft;  large  fires  are  constantly  main- 
tained at  the  bottom  of  the  latter,  the  air  is  drawn  down  the 


VENTILATION  AND  HEATING. 


107 


former,  diverted  through  all  parts  of  the  mine  by  partitions, 
and  finally  heated  and  carried  up  the  extraction  shaft. 

\Ve  may  also  use  a  jet  of  steam  or  water  in  place  of  heat 
to  extract  air  through  a  shaft,  the  openings  of  the  foul-air 
ducts  being  back  of  or  behind  the  jet.  It  is  said  that  a 
steam  jet  may  thus  set  in  motion  over  two  hundred  times  its 


FIG.  18. 


Air  propeller,  with  electric  motor  attached. 

own  bulk  of  air.  Lastly,  fans  driven  by  steam  or  water- 
power  have  been  employed  to  extract  the  air,  though  these 
are  usually  more  efficient  in  forcing  in  air.  For  instance, 
one  of  36  inches  diameter,  at  600  revolutions  per  minute 
will  extract  over  18,000  cubic  feet  of  air  per  minute. 
In  ventilation  by  propulsion  or  forcing  in  air,  these 


108     A  MANUAL  OF  HYGIENE  AND  SANITATION. 

large  revolving  fans  are  generally  used.  The  advantages 
of  this  system  of  ventilating  are  the  certainty  as  to  the 
direction  of  current  and  amount  of  air  supplied,  and  the 
ease  with  which  the  quantity  can  be  altered  or  measured. 
The  disadvantages  are  the  high  cost  of  power  in  most 
cases,  the  inconvenience  or  danger  from  prolonged  stop- 
page from  accidents  to  the  apparatus,  and  some  difficulty 
in  distributing  the  air.  For  instance,  if  it  be  forced  in 
through  small  openings  or  at  too  great  a  velocity  it  will 
not  mix  properly  with  the  air  of  the  room .  The  increased 
use  of  electric  motors  and  lowered  cost  of  running  them 
will  doubtless  serve  to  make  this  system  of  ventilation 
more  common  in  the  near  future. 

House  Warming-.  In  cold  countries  there  must  be 
some  resort  to  artificial  heat  in  the  winter  season,  and  as 
this  subject  is  more  or  less  inseparably  and  closely  con- 
nected with  ventilation,  it  may  be  appropriately  consid-. 
ered  at  this  time.  Cold  is  depressing,  uncomfortable,  and 
dangerous  to  the  young  and  aged,  and  to  women  whose 
habits  of  life  keep  them  much  indoors;  though  well-fed, 
healthy,  adult  men  may  not  be  much  affected,  if  accus- 
tomed to  it.  In  this  country  we  need  a  higher  tempera- 
ture in  our  houses  than  in  Great  Britain,  on  account  of 
our  drier  climate;  evaporation  and  consequent  cooling  of 
the  body  take  place  more  rapidly  here,  and  so,  while  they 
are  accustomed  to  a  temperature  from  60°  to  65°  F.,  we 
find  from  65°  to  75°  F.  to  be  no  more  than  comfortable. 

It  needs  but  slight  investigation  to  determine  that  we 
practically  make  use  of  but  two  kinds  of  heat — radiant 
and  convected — in  the  heating  of  houses,  and  that  of  these 
the  latter  is  by  far  the  most  generally  employed  and  the 
most  economical.  Radiant  heat,  although  it  is  the  most 
healthful  and  warms  an  object  directly  without  raising  the 


VENTILA  TION  AND  HE  A  TING.  109 

temperature  of  the  intervening  air,  has  the  disadvantages 
of  utilizing  but  a  small  proportion  of  the  fuel  value,  of 
decreasing  directly  as  the  square  of  the  distance  of  the 
object  from  the  source  of  heat,  and  of  being  available  only 
in  comparatively  small  apartments.  Our  best  example 
of  radiant  heat  is  that  which  conies  from  open  fires,  though 
any  highly-heated  object,  as  a  stove,  gives  off  more  or  less 
of  it.  Heat  that  is  carried  from  one  place  to  another  by 
heated  masses  of  air,  water,  or  steam,  is  said  to  be  con- 
vected,  and  because  of  the  economy  in  its  use  and  the  ease 
of  distribution,  especially  in  large  spaces,  it  is  the  kind 
most  generally  used.  Conducted  heat,  which  passes  from 
molecule  to  molecule  of  the  conducting  substance,  acts  too 
slowly  to  be  available  to  any  extent  in  house-heating,  and 
may,  therefore,  be  omitted  from  this  discussion. 

Just  here  it  may  be  remarked  that,  under  present  condi- 
tions, there  are  three  things,  any  two  of  which  we  may  have, 
but  not  all  three  together,  except  in  rare  instances :  they 
are  good  ventilation,  efficient  heating,  and  cheapness. 
The  reason  for  this  is  that  any  good  system  of  ventilation 
necessarily  and  continually  carries  off  a  large  quantity  of 
air  with  its  contained  heat,  which  latter  is  lost  for  heating 
purposes  and  must  be  replaced  at  the  expense  of  more  fuel. 
A  heat  unit  cannot  be  used  at  the  same  lime  to  produce 
ventilation  and  to  heat  objects  other  than  the  air  it  keeps 
in  motion.  The  principal  aim,  then,  in  establishing  any 
system  of  combined  ventilation  and  heating  must  be  to 
heat,  introduce,  and  carry  off  no  more  air  than  is  necessary 
for  the  requirements  of  good  ventilation  and  health,  and 
to  produce  the  heat  for  warming  this  air  and  the  house 
itself  as  economically  as  possible;  though  care  must  also 
be  had  to  secure-  evenness  of  distribution,  absence  of 
draughts,  etc. 


HO    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

The  usual  appliances  for  house-heating  are  open  grates 
or  fireplaces,  stoves,  and  hot-air,  steam,  and  hot- water  fur- 
naces. To  these  may  now  be  added  electrical  heaters,  but 
the  cost  of  maintaining  them  at  present  prevents  their  use 
by  any  but  the  wealthy. 

Ordinary  grates  and  open  fireplaces  give  practically  only 
radiant  heat,  and  render  available  only  from  7  per  cent,  to 
12  per  cent,  of  the  fuel  efficiency.  They  also  only  heat 
directly  the  surfaces  of  objects  facing  them,  leaving  the 
remainder  cold;  and  by  reason  of  the  great  current  up  the 
chimney  are  also  apt  to  bring  in  large  quantities  of  air  from 
without  that  has  not  been  properly  warmed,  and  to  thus 
cause  injurious  draughts.  Where  there  is  some  additional 
means  of  heating  the  air  before  it  enters  the  apartment, 
and  where  the  chimney  current  is  controlled  by  a  damper, 
they  are  valuable,  not  only  for  the  good  ventilation  they 
produce,  but  for  the  pleasing  effect  of  the  exposed  fire. 

To  make  open  grates  most  effective  for  heating,  the  sides 
and  top  should  be  inclined  to  the  back  at  an  angle  of  135°, 
so  as  to  throw  as  many  heat-rays  as  possible  into  the  room; 
the  fuel  surface  should  be  concentrated,  and  there  should 
be  a  damper  to  prevent  too  rapid  combustion  and  too 
much  heat  and  air  escaping  up  the  chimney.  It  is  to  be 
understood,  of  course,  that  the  objects  warmed  by  the 
radiant  heat  of  the  open  fire  do  in  turn  give  us  convected 
heat  by  warming  the  air  surrounding  them. 

If,  however,  the  back  and  sides  of  these  grates  be  sur- 
rounded by  a  space  through  which  the  air  can  pass  and  be 
warmed  by  the  heat  that  would  be  otherwise  wasted,  we 
shall  have  a  much  better  heating  apparatus,  since  we  thus 
get  both  radiant  and  convected  heat,  and  may  obtain  from 
25  per  cent,  to  35  per  cent,  of  our  fuel  efficiency.  And 
if  outdoor-air  be  let  into  this  air-space  and  warmed,  the 


VENTILATION  AND  HEATING.  HI 

ventilation  will  be  greatly  improved,  other  inlets  will  be 
unnecessary,  uncomfortable  draughts  will  be  avoided,  and 
there  will  be  enough  heat  provided  for  one  or  more  apart- 
ments of  moderate  size.  The  air-chamber  at  the  back 
should  not  be  too  small,  and  there  should  be  as  much 
heated  surface  to  warm  the  incoming  air  as  possible. 

FIG.  19. 


Jackson's  ventilating  grate.    The  outer  casing  is  cut  away  to  show  space  and 
surface  for  warming  the  incoming  air. 

Stoves  utilize  a  considerable  percentage  of  the  fuel — 
75  to  80  per  cent,  or  more — but  do  not  remove  much  air ; 
so  ventilation  has  to  be  provided  for  in  some  other  way 
and  is  apt  to  be  neglected.  Stoves  may  also  give  off  dan- 
gerous gases  and  products  of  combustion  if  not  properly 
cared  for,  or  if  the  damper  in  the  stovepipe  be  entirely 
closed.  There  should  be  as  much  surface  exposed  as  is 
possible  without  diminishing  the  heating  capacity,  so  that 
there  may  be  much  radiant  he,at.  It  is  often  advisable, 
especially  in  assembly  or  school-rooms  and  the  like,  to 
surround  the  stove  with  a  sheet-iron  cylinder  extending 
from  the  floor  toward  the  ceiling,  and  to  bring  in  between 
this  and  the  stove  a  supply  of  fresh  air  from  without. 


112    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

This  air  becomes  heated  and,  passing  out  over  the  top  of 
the  cylinder  or  drum,  gives  a  plentiful  supply  of  convected 
heat,  together  with  good  ventilation.  A  suitable  outlet 
must,  of  course,  be  provided.  Carbon  monoxide  and  other 
gases  are  known  to  leak  through  cast-iron  when  it  is  too 
highly  heated,  so  that  stoves  should  not  be  allowed  to  be- 
come too  hot. 

Other  objections  to  stoves  that  are  allowed  to  become 
too  hot  are  the  excessive  dryness  of  the  atmosphere  which 
they  cause,  and  the  unpleasant  odor  due  to  the  scorching 
of  floating  organic  substances  that  come  in  contact  with 
the  hot  iron. 

The  fuel  most  commonly  used  in  both  grates  and  stoves 
is  either  wood  or  some  kind  of  coal  (bituminous,  anthra- 
cite, or  cannel);  but  gas  may  often  be  advantageously  em- 
ployed instead  of  any  of  these,  since  the  heat  can  be  had 
from  it  practically  instantaneously,  can  be  closely  regu- 
lated in  quantity,  and  can  be  promptly  checked  when  no 
longer  desired,  and  since  there  is  no  production  of  dust  or 
ashes  in  the  room.  The  main  objection  to  gas  is  that  for 
large  rooms  or  prolonged  or  continuous  heating  it  is 
usually  more  expensive  than  the  other  fuels;  but  this  does 
not  hold  good  for  small  rooms,  and  sometimes  for  isolated 
apartments,  or  where  the  warmth  is  needed  only  tempora- 
rily; and  it  is  very  probable  that  before  long  fuel  gas  will 
be — it  can  be  now — supplied  at  rates  which  will  justify  a 
much  more  extended  use  of  such  fuel. 

The  ordinary  kinds  of  gas-grates  and  stoves,  especially 
those  which  consume  the  gas  incompletely,  should  all  be 
constructed  with  flues  to  carry  off  the  products  of  com- 
bustion directly,  and  this  particularly  when  any  large 
quantity  of  gas  is  used.  Theoretically,  when  the  gas  is 
burned  in  a  properly  adjusted  Bunsen  or  "  atmospheric" 


VENTILATION  AND  HEATING. 


113 


burner,  the  only  combustion  products  will  be  carbonic  acid 
and  water,  the  former  of  which  is  rapidly  diffused  into 
the  outer  air,  as  has  been  shown,  and  is  not  likely  to  be 
harmful  in  any  quantities  thus  produced,  while  the  aque- 
ous vapor  is  beneficial  to  the  atmosphere  rather  than  other- 
wise. However,  it  seems  that  in  practice  even  these  Bunsen 
burners  may  sometimes  give  to  the  air  a  disagreeable  odor 
(said  to  be  due  to  the  formation  of  acetylene),  and  so  need 
flue  connections. 


FIG.  20. 


Section  of  Backus'  portable  steam  radiator  for  use  with  gas. 

In  this  connection  it  may  be  interesting  to  describe  one 
form  of  gas-heater  which,  so  far  as  the  writer  knows,  is 
unique.  It  is  intended  not  only  to  consume  perfectly  the 
gas  it  uses,  giving  nothing  to  the  air  but  carbonic  acid 
and  water,  but  also  to  destroy  by  fire  the  impurities  of  the 
atmosphere  of  the  room,  thus  doing  away  with  chimneys 

8 


114    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

or  flues  and  the  necessity  of  much  ventilation.  By  a 
peculiar  arrangement,  a  continued  current  of  air  is  made 
to  pass  through  the  flame,  thus  burning  the  impurities, 
whether  gaseous  or  solid.  The  heat  of  the  burning  gas  is 
also  used  to  convert  a  quantity  of  water  into  steam,  thus 
warming  the  containing  chamber  or  coils  of  pipe,  and  these 
in  turn  the  air  surrounding  them,  in  this  way  warming 
many  times  the  volume  of  air  possible  to  heat  by  the  flame 
alone.  In  addition,  the  normal  humidity  is  maintained 
in  the  atmosphere  by  the  evaporation  of  water  from  an 
open  basin  beneath  the  fire. 

The  ordinary  openings  of  any  room  are  amply  sufficient 
to  allow  the  diffusion  of  the  excess  of  carbonic  acid — one- 
half  escaping  in  this  way,  according  to  Roscoe,  within 
ninety  minutes — and  to  permit  the  ingress  of  enough  air 
fully  to  supply  all  the  needs  of  the  inmates  and  of  the  fire 
itself.  Experience  and  careful  experiments  seem  to  show 
that  the  claims  of  the  inventor  are  well  founded  and  that 
the  apparatus  is  healthful  in  its  operation  and  produces 
no  harmful  effects,  even  after  continued  use  for  several 
months. 

At  any  rate  there  seems  to  be  no  reason  why  we  may 
not  purify  the  air  by  fire  instead  of  by  dilution  and  re- 
moval, the  methods  employed  in  the  hitherto  described 
systems  of  ventilation. 

Oil-stoves  are  now  used  quite  extensively  and,  beside 
being  portable,  have  the  same  advantages  as  gas-stoves, 
viz.,  that  a  considerable  quantity  of  heat  may  be  had 
quickly  and  just  as  long  as  it  is  desired,  and  at  a  fairly 
moderate  cost.  The  combustion  products  necessarily  mix 
directly  with  the  atmosphere  of  the  room,  and  where  rea- 
sonably perfect  burning  is  had  doubtless  consist  of  little 
else  than  carbonic  acid  and  water.  One  pound  of  oil,  the 


VENTILATION  AND  HE  A  TING.  1 1 5 

hourly  consumption  of  a  rather  large  stove,  will  require 
about  150  cubic  feet  of  air  for  its  complete  combustion, 
and  will  produce  about  twenty-five  cubic  feet  of  carbon 
dioxide. 

"  We  do  not  think  that  the  experience  has  yet  been 
accumulated  which  would  enable  us  to  speak  positively 
of  the  innocuousness  of  a  considerable  admixture  of  car- 
bonic acid  with  the  air  we  breathe,  but  the  knowledge  that 
in  hundreds  of  cases  oil-stoves  are  used  for  heating  living 
rooms  and  even  bedrooms  without  apparent  injury  to  the 
occupants  makes  one  feel  fairly  confident  that  the  prod- 
ucts of  the  complete  combustion  of  hydrocarbons  are  not 
injurious  when  mixed  with  such  an  amount  of  air  as  is 
sufficient  to  dilute  to  a  proper  degree  the  respiratory  prod- 
ucts. .  .  .  Experiments  show  that,  provided  the 
combustion  of  the  oil  is  complete,  and  that  the  ventilation 
is  sufficient  for  the  ordinary  effects  of  respiration,  the  use 
of  oil-stoves  for  heating  purposes  may  be  advantageously 
employed  in  both  day-  and  sleeping-rooms.  The  efficiency 
of  oil-stoves  is  increased  by  placing  over  them  a  diffuser 
or  radiator,  so  as  to  prevent  the  heated  products  ascending 
direct  to  the  ceiling;  care  needs  also  to  be  taken  that  only 
the  better  kinds  of  mineral  oil  are  used;  if  inferior  quali- 
ties of  oil  are  burnt  perfect  combustion  is  more  difficult 
to  obtain."1 

The  above  remarks,  as  far  as  they  apply  to  the  health- 
ful use  of  the  air,  may  probably  be  used  with  equal  justice 
in  regard  to  gas-stoves,  provided  that  with  such  dilution, 
their  products  give  no  obviously  harmful  or  disagreeable 
results. 

The  heating  apparatus  thus  far  described  is  such  as  we 

i  Notter  and  Firth,  p.  228. 


116    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

are  accustomed  to  employ  for  warming  the  air  of  single  or, 
possibly,  of  adjoining  rooms.  Where  a  whole  dwelling  or 
other  large  building  is  to  be  heated,  it  will  usually  be  of 
advantage  to  do  this  from  one  point,  and  that  not  in  any 
of  the  living  apartments.  In  this  way  we  shall  have  a 
centralization  of  fuel,  both  unburned  and  burning,  and  the 

FIG.  21. 


Spear's  hot-air  furnace. 


ability  to  derive  more  heat  from  it;  a  lessening  of  the  labor 
and  attention  bestowed  on  the  fires;  the  obviation  of  much 
dust,  dirt,  and  combustion-products  in  living-rooms,  and, 
presumably,  a  more  equable  and  satisfactory  warming  of 
the  whole  building.  From  such  a  central  point  the  heat 


VENTILA  TION  AND  HE  A  TING.  \  \  7 

is  distributed  by  hot  air,  hot  water,  or  steam,  or  by  hot  air 
in  combination  with  either  of  the  other  two. 

Hot-air  furnaces  supply  a  large  amount  of  convected, 
but  no  radiant  heat.  There  is  a  very  prevalent  opinion 
that  they  are  not  healthful  and  that  wherever  possible 
they  should  be  substituted  by  some  other  means  of  heat- 
ing; but  when  properly  constructed  and  cared  for  a  hot- 
air  furnace  of  the  proper  size  is  not  only  a  good  heater,  but 
a  powerful  ventilating  agent;  for  the  large  supply  of  air 
passing  through  it  into  the  rooms  above  must  in  time  find 
an  exit  either  through  specially  devised  outlets  or  through 
the  innumerable  cracks  and  crevices  around  all  doors  and 
windows,  and  the  ventilation  will  be  accordingly. 

One  frequent  source  of  trouble  is  too  small  a  fire-pot, 
giving  insufficient  heating  surface  and  necessitating  too 
rapid  and  too  intense  combustion  of  fuel.  There  should 
be  a  considerable  expanse  of  surface,  never  too  highly 
heated,  so  that  large  volumes  of  air  will  be  moderately 
warmed,  rather  than  small  quantities  over-heated  and 
"  burned."  Air  too  highly  heated  is  very  dry  and  offen- 
sive to  the  senses — also,  by  taking  excessive  moisture  from 
the  body  through  the  skin  and  mucous  membrane,  it 
increases  the  liability  to  frequent  "  colds"  and  conges- 
tions. Moreover,  a  large  quantity  of  air  moderately 
warmed  will,  perforce,  be  carried  to  all  the  rooms  of  the 
house,  warming  them  equably  and  driving  before  it  the 
air  already  there:  whereas,  a  much  smaller  volume,  exces- 
sively heated  by  the  same  or  even  a  greater  amount  of 
fuel,  will  make  its  way  along' the  channels  of  least  resist- 
ance to  certain  favored  rooms,  overheating  them  and 
•keeping  the  rest^of  the  house  cold,  beside  preventing  any 
satisfactory  natural  ventilation. 

All  joints  in  the  furnace  must  be  as  near  gas-tight  as 


118    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

possible,  to  prevent  the  combustion  products  passing  from 
the  fire-box  or  smoke-flues  into  the  air  chambers  and 
thence  into  the  house. 

FIG.  22. 


Hot-air  furnace,  showing  cold-air  inlet  and  hot-air  flues.    Only  one  of  the  lateral 
branches  of  the  main  inlet  above  is  shown. 

The  furnace  should  be  located  near  the  cold  side  of  the 
house — that  is,  the  side  on  which  the  prevailing  cold  winds 
impinge,  for  it  is  said  to  be  as  difficult  to  drive  the  air  ten 


VENTILATION  AND  HEATING.  1 1 9 

feet  against  the  wind  as  forty  or  fifty  feet  with  it.  It  may 
also  be  well,  if  the  basement  ceiling  is  low,  to  place  the 
ash-pit  even  below  the  level  of  the  basement  floor,  in  order 
to  give  sufficient  slope  to  the  air-ducts;  but  in  every  case 
the  space  beneath  the  furnace  should  be  cemented  or  laid 
in  asphalt  to  prevent  the  drawing  in  of  soil-air. 

The  air-supply  should  not  be  taken  from  the  cellar,  even 
though  the  latter  be  apparently  clean  and  free  from  any 
contamination  with  soil-air,  but  should  come  from  a  clean 
source  out  of  doors,  well  above  the  ground-level  and  from 
the  direction  of  the  prevailing  winds.  The  cold- air  duct  or 
ducts  should  be  screened  at  the  entrance  to  prevent  the 
admission  of  refuse  or  vermin,  should  be  arranged  to  permit 
of  regular  cleaning,  should  have  a  damper  to  regulate  the 
supply  of  air,  and  should  have  a  cross-section  of  at  least 
two-thirds  of  the  combined  area  of  the  hot-air  flues  lead- 
ing from  the  furnace.  It  may  be  desirable  to  provide  for 
the  filtration  of  the  air  through  coarse  cloth  or  fine  wire 
gause,  especially  if  there  be  much  dust  in  the  incoming 
air. 

If  possible,  the  hot-air  flues  or  ducts  should  not  be  flat, 
but  round  or  square,  to  lessen  the  friction,  and  should  be  as 
direct  in  their  course  and  as  nearly  vertical  as  possible  for 
the  same  reason.  They  should  be  covered  from  the  fur- 
nace to  the  register  openings  with  asbestos  or  other  non- 
conducting material,  to  prevent  the  loss  of  heat  that 
otherwise  escapes  from  them  into  the  cellar  and  between 
the  partitions.  Lastly,  their  register-openings  into  the 
rooms  should  not  face  the  windows  or  prevailing  winds, 
unless  absolutely  unavoidable,  for  if  they  do,  the  passage  of 
warm  air  into  the  room  will  often  be  completely  checked. 

The  following  table,  from  Coplin  and  Be  van,  will  indi- 
cate the  proper  size  for  hot-air  flues  and  registers  : 


120    A  MANUAL  OF  HYGIENE  AND  SANITATION. 


FIRST  FLOOR. 


Size  of  room  in  cubic 
feet. 

Size  of  pipe. 

Size  of  register. 

If  round. 

If  square. 

If  round.        If  square. 

Less  than  1500    . 

7  inches 

4x9  inches 

9  inches     7  x  10  inches 

1500  to  2000      . 

8        " 

4  x  12      " 

10       "         8x10      " 

2000  to  3000      . 

9       " 

4x16      "             12        "          8x12      " 

3000  to  4000      . 

10       " 

4  x  18      " 

12       "          9x14      " 

Economy  will  be  subserved  in  most  cases  by  taking  care 
to  burn  the  fuel  in  hot-air  furnaces  quite  slowly,  since  in 
this  way  larger  quantities  of  air  are  warmed  and  more 
satisfactorily,  and  there  is  also  less  waste  of  heat  through 
the  smoke-flues  and  up  the  chimney.  Moreover,  it  is  the 
experience  of  the  writer,  that  by  working  the  furnace  in 
this  way  at  low  pressure,  so  to  speak,  the  air  from  it  will 
practically  never  be  too  dry,  nor  need  the  addition  of 
moisture,  something  essentially  necessary  and  yet  most 
often  neglected  where  too  little  air  is  excessively  heated. 

When  it  is  necessary  to  carry  heat  for  a  considerable 
distance  or  to  warm  large  buildings  or  blocks  of  buildings 
from  a  central  point,  it  will  be  better  and  more  economical 
to  employ  hot  water  or  steam  as  the  heat-transmitting 
agent,  on  account  of  the  high  specific  heat  of  the  former 
and  the  great  amount  of  latent  heat  held  by  the  latter. 
"  It  is  uneconomical  to  convey  heated  air  any.  long  dis- 
tance, as  the  amount  of  heat  conveyed  per  cubic  foot  of 
air  raised  to  any  practical  temperature  is  so  small  and  so 
easily  lost  in  transit.  On  this  account  Morin  considers 
the  availability  (of  hot-air  furnaces)  limited  to  a  horizontal 
range  of  forty  or  forty-five  feet  from  the  heating  appa- 
ratus."1 

1  Stevenson  and  Murphy,  vol.  i.  p.  117. 


VENTILATION  AND  HEATING.  121 

An  equal  quantity  of  heat,  viz.,  one  thermal  unit,  is 
required  to  raise  one  pound  of  water  or  fifty  cubic  feet  of 
air  1°  F.,  and  accordingly  water  will  carry  over  four 
(4.21)  times  as  much  heat  as  an  equal  weight  of  air  at 
the  same  temperature.  "  Further,  a  greater  effect  is  pro- 
duced when  water,  in  the  form  of  steam,  is  made  the  car- 
rier of  heat,  because  one  pound  of  water — vapor — at  100° 
C.  (212°  F.)  will,  in  condensing  to  form  boiling  water, 
give  off  sufficient  heat  to  raise  the  temperature  of  5.36 
pounds  of  water  (or  4.21  X  5.36  =22.5  pounds  of  air) 
from  0°  C.  to  100°  C.  (32°  F.  to  212°  F.)." 

Hot-water  heating  may  be  by  either  the  low-pressure  or 
the  high-pressure  system.  In  the  former  large  pipes  (gene- 
rally four  inches  in  diameter)  are  used,  and,  the  system 
being  open  to  the  air  at  its  highest  point,  the  temperature 
of  the  water  can  never  be  much  above  212°  F.  at  any  part 
of  the  system.  The  water  circulates  comparatively  slowly, 
but,  owing  to  the  large  volume,  conveys  much  heat  from  the 
furnace  to  the  places  where  it  is  needed.  The  high-presnre 
system  employs  small  but  very  strong  pipes,  the  water  being 
completely  inclosed  from  the  outer  air,  wherefore  it  attains 
a  high  temperature,  usually  about  300°  F.,  and  circulates 
rapidly.  The  necessary  expansion  is  provided  for  by  larger 
pipes  partly  filled  with  air  at  the  top  of  the  circuit.  The 
maximum  temperature  is  regulated  by  the  proportion  of 
pipe  exposed  to  the  fire,  usually  one-tenth.  Either  of  the 
hot-water  systems,  but  especially  the  low,  require  careful 
planning  and  setting  to  maintain  evenness  of  circulation; 
but  when  the  latter  is  complicated,  as  by  many  radiators  at 
various  levels,  or  where  a  number  of  circulations  have  to 
be  supplied  from  the  same  boiler,  it  may  be  very  difficult  to 
maintain  an  even  head  and  an  equable  distribution  of  heat 
in  all.  "  If  properly  constructed  and  the  heating  planned 


122    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

for  when  the  house  plans  are  made,  this  hot-water  system 
is  probably  the  most  economical,  both  in  fuel  used  and 
repairs  demanded. "l 

Steam-heating  methods  are  usually  quite  satisfactory, 
not  only  because  of  the  large  quantity  of  heat  carried, 
but  also  since  a  rapid  circulation  is  readily  maintained, 
even  under  adverse  circumstances.  The  size  of  pipe  used 
will  depend  on  the  extent  of  the  distribution,  but  the 
calibre  of  the  radiator  should  always  be  considerably  larger 
than  that  of  the  supply  pipes,  in  order  to  favor  conden- 
sation and  the  consequent  liberation  of  latent  heat,  and 
every  facility  should  be  provided  for  the  speedy  return*  of 
the  condensed  vapor  to  the  boiler.  Care  must  also  be 
taken  to  prevent  the  condensation  occurring  in  such  a  way 
as  to  cause  obstruction  to  the  flow  of  the  steam  and  the 
disagreeable  thumping  and  noise  that  result. 

With  either  steam-  or  hot-water  heating,  the  direct,  the 
indirect,  or  the  direct-indirect  method  of  radiation  may  be 
used.  Of  these  the  direct  method — that  is,  where  the 
radiators  are  placed  in  the  rooms  to  be  warned — is  most 
commonly  employed  in  dwellings  and  other  buildings  of 
moderate  size;  but  it  is  open  to  the  objections  that  in 
itself  it  does  not  bring  about  a  sufficient  change  of  air, 
that  the  necessary  inlets  and  outlets  for  the  latter  are 
rarely  provided,  and  that  when  present  they  are  indepen- 
dent of  the  heating  system  of  the  house.  Of  course,  these 
objections  are  removed  when  the  direct  is  combined  with 
the  indirect  method,  or  when  a  plentiful  supply  of  pure 
air  is  brought  from  without  and  is  warmed  by  being  made 
to  pass  through  the  radiators  (either  open  or  enclosed  in 
boxing)  before  diffusing  through  the  room,  this  being  the 

1  Coplin  and  Sevan,  p.  325. 


VENTILATION  AND  HEATING. 


123 


direct-indirect  method.  In  the  indirect  method  the  radi- 
ators are  placed  in  suitable  and  convenient  enclosures  out- 
side of  the  room,  into  which  fresh  air  is  brought  from  out 
of  doors  and  from  which  the  warmed  air  is  conveyed  by 
suitable  ducts  to  the  respective  rooms  above.  If  properly 

FIG.  23. 


Steam  radiators  and  blower  used  in  warming  the  clinical  amphitheatre  of  the 
Medico-Chirurgical  College  of  Philadelphia,  by  the  indirect  system.  (The  casing 
of  the  radiators  is  not  yet  applied.)  Tempering  radiator  at  left ;  warming  radiator 
at  right ;  casing  of  fan  between. 


arranged,  both  the  indirect  and  the  direct-indirect  methods 
should  furnish  good  and  ample  ventilation,  the  incoming 
warm  air  pushing  the  used  air  of  the  room  ahead  of  it 
through  the  various  openings  in  the  walls  of  the  room. 


124    ^  MANUAL  OF  HYGIENE  AND  SANITATION. 

Safety  valves  on  steam  boilers  prevent  any  danger  from 
explosions,  and  automatic  thermo-regulators  make  it  pos- 
sible to  maintain  a  practically  even  temperature  through- 
out the  house  or  building  at  all  times. 

In  the  Clinical  Amphitheatre  of  the  Medico -Chirurgical 
College  of  Philadelphia,  the  indirect  system  is  employed, 
the  details  being  as  follows  :  The  cold  air  is  brought  from 
near  the  roof-level  by  a  large  shaft  into  the  cold-air  room, 
where  it  is  moistened  by  a  spray  and  whence  it  passes 
through  a  dust-filter,  consisting  of  a  double  layer  of  fine 
wire  gauze.  Thence  it  passes  through  tempering  radia- 
tor (to  modify  the  temperature)  into  the  revolving  fan, 
driven  by  its  own  engine,  whence  part  passes  through  a 
second  and  larger  radiator  to  be  farther  warmed,  and  part 
below  the  latter,  the  two  currents  again  uniting  and,  after 
mixing,  passing  through  the  flues  into  the  amphitheatre 
above.  In  this  the  temperature  is  regulated  by  a  thermo- 
stat (which  governs  a  damper  not  shown  in  the  cut)  which 
always  permits  the  same  volume  of  air  to  pass  into  the 
flues,  but  controls  the  respective  quantities  of  heated  and 
tempered  air,  so  that  the  mixture  practically  does  not  vary 
in  temperature.  In  this  way  900,000  cubic  feet  of  air  at 
a  fixed  temperature  can  be  supplied  per  hour. 

For  the  private  operating-rooms  the  system  is  the  same, 
except  that  the  tempered  and  the  heated  air  are  not  mixed, 
but  each  is  carried  by  separate  flues  to  double  registers  in 
the  operating-rooms.  In  this  way  each  operator  can  have 
the  temperature  that  he  desires  in  his  room  at  any  time. 

In  very  large  buildings  it  may  be  advisable  or  necessary, 
as  above,  to  drive  the  air  heated  by  the  indirect  method 
into  the  rooms  (the  plenum  or  propulsion  system),  or  to 
withdraw  it  through  special  outlets  by  suction  (the  exhaust 
system).  Of  these  the  former  is  preferable,  since  the 


VENTILATION  AND  HEATING.  125 

source  from  which  the  air  is  taken  aijd  the  inflow  through 
the  heating  apparatus  are  both  more  certain. 

To  determine  the  amount  of  radiating  surface  needed 
for  any  room  we  must  multiply  the  volume  of  air  to  be 
heated  per  hour  by  the  difference  between  its  temperature 
in  degrees  Fahrenheit  before  and  after  warming,  and 
divide  this  product  by  50,  the  quantity  of  air  in  cubic  feet 
raised  1°  F.  by  one  thermal  unit.  This  will  give  the 
number  of  heat  units  required  to  warm  the  air.  Then 
this  quotient  must  be  divided  by  the  difference  between 
the  temperature  of  the  radiating  surface  and  that  of  the 
air  when  finally  warmed  multiplied  by  1.75,  the  number 
of  thermal  units  given  off  per  hour  by  one  square  foot  of 
hot  water  or  steam-pipe  for  each  Fahrenheit  degree  of 
heat  it  loses.  This  will  give  the  area  of  hot  water  or 
steam-pipe  required  to  warm  the  given  volume  of  air. 
Thus,  to  warm  6000  cubic  feet  of  air  per  hour  from  20° 

to  70°   F.   will  require  6QQO  *  (70  —  20)  =  6000  heat 

ou 
units,  and  if  the  surface  of   the  radiator  be  200°  F., 


(200°  —  70°)  X  1.75 
of  radiating  surface  needed.  To  this  must  be  added  at 
least  one-half  square  foot  for  each  square  foot  of  window 
glass  and  'for  each  square  yard  of  outer  wall  exposed. 


CHAPTER    V. 

WATER. 

NEXT  to  air,  water  is  the  most  important  of  all  sub- 
stances necessary  to  human  life.  While  it  has  been  often 
demonstrated  that  man  may  do  without  food  for  a  consid- 
erable length  of  time,  even  for  several  weeks,  he  can 
probably  not  survive  much  more  than  ten  days  without 
water.  But  not  only  must  we  have  enough  to  supply  the 
internal  wants  of  the  body  and  to  replace  that  lost  by 
excretion,  evaporation,  and  respiration;  but  from  a  sani- 
tary point  of  view,  a  plentiful  supply  is  needed  to  maintain 
cleanliness  of  bodies,  clothing,  and  dwellings,  and,  often- 
times, to  remove  sewage,  excreta,  etc.,  from  the  vicinity  of 
inhabited  places.  The  care  of  furnishing  water  in  abun- 
dance and  of  maintaining  its  purity  is,  therefore,  entirely 
within  the  domain  of  the  physician  and  the  sanitarian. 

Before  inquiring  into  the  source  whence  we  obtain  the 
water  that  we  use  it  will  be  well  to  know  what  amount  is 
required  by  the  body  for  its  daily  needs,  and  how  much 
for  other  necessary  purposes,  so  that  we  may  be  able  to 
judge  not  only  whether  a  given  source  furnishes  pure 
water,  but  also  whether  it  gives  a  sufficient  supply  of  it. 

The  average  adult  should  take  from  seventy  to  one 
hundred  fluidounces  per  day  for  nutrition  and  the  internal 
needs  of  the  body  alone — about  one -third  of  this  being  a 
component  part  of  the  food,  and  the  rest  being  taken  in 
as  drink.  The  writer  is  of  the  opinion  that  the  average 
person  does  not  imbibe  enough  water  for  the  most  health- 


WATER.  127 

ful  action  of  his  tissues  and  organs.  Certain  it  is  that  in 
most  cases  the  plentiful  use  of  a  good  drinking-water  not 
only  greatly  favors  the  body  metabolism,  but  also  materi- 
ally assists  in  the  flushing  out  and  carrying  away  of  the 
various  wastes  and  excreta  of  the  system. 

In  addition  to  this  we  must  supply  a  sufficiency  for 
cooking  and  for  washing  the  food,  body,  clothing,  house- 
hold utensils,  and  parts  of  the  house  itself,  and  to  remove 
the  household  waste  and  sewage  through  the  drains  and 
sewers  provided  for  that  purpose.  Cleanliness  is  an  essen- 
tial requisite  for  the  preservation  of  health,  and  cleanly 
habits  should  be  inculcated  among  all  classes  of  people, 
and  every  facility  provided  for  removing  filth  of  all  kinds 
from  persons,  clothes,  and  dwellings.  This,  of  course, 
cannot  be  done  without  a  fair  supply  of  water. 

Experience  shows  that  about  twenty-five  gallons  per 
head  per  day  should  be  furnished  for  the  above  purposes, 
and  as  the  quantity  used  by  domestic  animals,  manufactur- 
ing establishments,  municipal  needs,  etc.,  must  be  added 
to  this,  fifty  gallons  or  even  more  per  capita  should  be  sup- 
plied daily,  wherever  it  is  at  all  possible.  And  though  a 
supply  that  permits  of  excessive  waste  may  be  inadvisable 
and  expensive,  both  to  provide  and  by  increasing  the  cost 
of  carrying  it  away  after  use,  it  is  always  better  to  have 
too  much  than  too  little,  and  the  disadvantages  of  too 
scanty  an  amount  are  much  greater  than  those  of  one  too 
large. 

It  should  be  stated,  however,  that  most  foreign  cities  are 
supplied  with  much  less  water  per  capita  than  is  appar- 
ently needed  by  the  municipalities  of  this  country,  and 
yet  they  seem  to  have  an  abundance  for  all  necessary  pur- 
poses and  the  requirements  of  public  health.  For  instance, 
London,  with  a  population  of  over  five  millions,  has  an 


128    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

average  daily  supply  that  but  slightly,  if  at  all,  exceeds 
that  of  Philadelphia,  with  one-fourth  the  number  of  citi- 
zens; while  Berlin,  which  is  of  about  the  same  size  as 
Philadelphia,  had  in  1893  an  average  daily  supply  of 
filtered  water  of  only  18.4  gallons  per  head,  all  of  which 
was  sold  to  the  consumers  by  meter,  but  to  which  must  be 
added  considerably  more  that  was  from  wells  and  was 
exclusively  used  for  manufacturing  purposes,  running 
machinery,  etc.  It  cannot  be  doubted  that  the  quantity 
wasted  in  many  of  the  cities  in  this  country  is  excessive, 
and  that  the  cost  of  supplying  that  part  of  the  total  quota 
would  go  a  long  way  toward  improving  and  rendering 
pure  and  safe  the  remaining  part  that  is  absolutely  needed. 
Whether  the  compulsory  use  of  water  meters  is  the  best 
way  of  bringing  about  an  improvement  in  this  respect 
remains  to  be  determined;  but  it  is  also  a  question  whether 
our  larger  cities,  with  rapidly  increasing  populations,  can 
afford  to  use  the  means  necessary  to  safely  purify  the 
enormous  quantity  of  water  now  daily  supplied  to  their 
respective  consumers. 

As  only  a  small  portion  of  the  quantity  indicated  above 
is  required  for  the  internal  needs  of  the  body,  it  has  been 
suggested  that  two  kinds  of  water  be  furnished — one  for 
drinking  and  cooking  purposes  and  for  the  washing  of  the 
body,  to  which  especial  attention  as  to  purity  should  be 
given;  and  another  kind  for  all  other  purposes,  its~com- 
position  and  purity  being  disregarded,  excepting  possibly 
as  concerns  the  hardness.  This  would  enable  the  authori- 
ties to  furnish  a  water  purer  than  usual  for  those  needs 
where  purity  is  of  the  greatest  importance,  and  would 
obviate  the  need  of  furnishing  pure  water  abundantly  for 
all  purposes;  but  the  scheme  would  necessitate  a  double 
set  of  reservoirs,  mains,  distributing  apparatus,  etc. ,  thus 


WATEE.  129 

materially  increasing  the  cost;  and  there  would  always  be 
present  the  danger  of  the  careless  or  ignorant  using  the 
impure  water  for  bodily  needs,  thus  increasing  the  risks 
and  bad  results  that  we  wish  to  avoid.  Therefore, 
wherever  there  can  be  an  abundance  of  pure  water  for  all 
personal  and  domestic  purposes,  if  the  authorities  but  take 
pains  to  furnish  it,  it  will  be  best  to  have  but  one  supply 
in  dwellings,  and  this  as  pure  and  abundant  as  money  and 
the  highest  sanitary  skill  can  make  it;  though  there  may 
be  little  or  no  objection  to  using  a  different  water  for 
factories,  stables,  city  uses,  etc. 

As  to  the  question  of  supply  through  meters,  it  may  be 
added  that  the  suggestion  has  been  made  that  the  regular 
charge  for  water  begin  only  after  a  certain  specified  amount 
per  month  per  capita  or  per  household  has  been  furnished 
free  or  at  the  lowest  possible  cost,  thus  d<5ing  away  with  the 
objection  that  those  who  need  the  water  most  for  personal 
and  sanitary  uses  would  be  tempted  to  economize  too 
much  if  they  had  to  pay  for  all  they  consumed.  Whether 
a  city  could  afford  to  do  this  would  have  to  be  carefully 
considered,  and  would  probably  depend  largely  upon  local 
circumstances. 

Sources.  Practically,  all  drinking-water  has  at  some 
time  or  other  fallen  upon  the  earth  from  the  air  in  the 
form  of  rain,  hail,  snow,  or  dew;  but  when  we  speak  of 
its  sources  we  have  reference  rather  to  the  place  or  locality 
from  which  we  collect  it  for  use.  The  rain  on  reaching  the 
earth  is  disposed  of  in  three  ways :  part  at  once  evaporates 
and  goes  back  to  the  atmosphere,  part  flows  off  according 
to  the  slope  of  the  ground  and  collects  in  pools  and  streams, 
and  part  sinks  into  the  soil.  The  ratio  which  these  three 
portions  will  bear  to  one  another  will  depend  on  the  time, 
place,  character  of  soil,  intensity  of  rainfall,  etc.  Conse- 


130    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

quently,  we  may  classify  the  sources  of  potable  waters — 
as  Leffmann  does — as  follows :  Rain-water,  collected  im- 
mediately as  it  falls  from  the  atmosphere,  in  the  form  of 
rain,  dew,  snow,  etc.;  surface-water,  collected  in  ponds, 
lakes,  streams,  etc.,  and  in  free  contact  with  the  atmos- 
phere; subsoil  or  ground  water,  derived  mainly  from  the 
rain  or  surface  water  of  the  district,  but  which  percolates 
and  flows  through  the  subsoil,  and  is,  therefore,  not  exposed 
directly  to  the  atmosphere;  deep  or  artesian  water,  which 
is  separated  from  the  ground  water  of  the  district  by 
one  or  more  practically  impermeable  strata,  and  which 
accumulates  at  a  considerable  depth  below  the  surface. 
Springs  are  caused  by  the  outcropping  of  water-bearing 
strata  below  the  level  of  the  water-line  in  them,  and  fur- 
nish either  subsoil  or  artesian  water,  according  to  the  kind 
contained  in  the  respective  strata. 

Raia-water  is,  theoretically,  the  purest  at  our  com- 
mand, but  in  reality  it  takes  up  many  impurities  from  the 
air  in  its  fall,  especially  in  the  neighborhood  of  human 
habitations,  and  communities,  and  by  the  time  it  reaches 
the  earth  contains  ammonia,  nitrous  and  nitric  acid,  and 
in  towns,  sulphurous  acid,  soot,  many  bacteria,  and  even 
microscopic  plants.  Moreover,  the  collecting  surface  upon 
which  it  falls  is  apt  to  be  covered  with  dust  and  impuri- 
ties of  all  kinds,  especially  after  continued  dry  weather, 
which,  being  taken  up  by  the  rain-water,  render  it  unfit 
for  use.  However,  if  there  be  some  arrangement  for  turn- 
ing aside  the  first  portion  of  rain  that  falls,  it  containing 
the  most  of  the  impurities,  and  if  the  remainder  be  filtered 
and  stored  in  proper  receptacles,  the  water  may  be  of 
excellent  quality. 

The  main  objection,  however,  to  the  sole  use  of  rain- 
water is  that  dependence  is  placed  upon  a  very  uncertain 


WATER. 

source,  and  one  which  is  especially  apt  to  fail  when  an 
increased  supply  is  most  needed.  The  average  rainfall  in 
Philadelphia  is  about  thirty-nine  inches  per  year;  in  very 
wet  years  it  is  about  one-third  more,  and  in  very  dry  years 
about  one-third  less  than  the  annual  average.  Each  inch 
of  rainfall  gives  4.67  gallons  per  square  yard  of  area  on 
which  it  falls,  equivalent  to  22,617  gallons  per  acre. 
Allowing  sixty  square  feet  of  collecting  surface  per  head, 
and  counting  the  loss  by  evaporation,  etc.,  at  20  per  cent., 
an  annual  rainfall  of  thirty  inches  would  give  only  about 
two  gallons  per  head  per  day,  or  just  about  enough  for 
cooking  and  drinking  purposes,  and  none  for  the  other 
needs  of  the  household. 

Rain-water  may  be  collected  from  roofs  or  from  a  plot 
of  ground  paved  for  the  purpose  with  slate  or  cement,  and 
led  by  proper  conduits  to  a  cistern.  It  should  be  filtered 
before  passing  into  the  cistern,  while  the  cistern  itself 
should  be  such  as  to  give  no  unpleasant  taste  or  injurious 
substance  to  the  water,  should  be  so  situated  that  it  will 
receive  no  rubbish  or  impurities  and  that  the  water  may 
be  kept  cool,  and  should  be  cleaned  regularly  and  often 
enough  to  keep  the  water  sweet  and  wholesome.  As  rain  - 
water  contains  considerable  carbonic  acid  and  other  gases, 
its  solvent  powers  are  marked,  and  cisterns  should  not  be 
lined  with  lead,  copper,  zinc,  or  iron,  lest  these  metals  be 
taken  up  by  the  water  and  produce  harmful  results. 
These  remarks  do  not  apply  to  the  so-called  rustless  iron 
now  much  used,  but  galvanized  iron  should  not  be  used, 
as  it  may  give  up  zinc  to  the  water. 

Cement  should  be  used  in  lining  brick  or  stone  cisterns 
instead  of  mortar,  as  the  latter  may  give  up  lime  to  the 
water  and  render  it  hard.  Underground  cisterns  for 
storing  rain-water  should  be  condemned,  since  they  are 


132-4  MANUAL  OF  HYGIENE  AND  SANITATION. 

liable  to  sewage  contamination  unless  absolutely  water- 
tight. The  overflow  pipe  from  a  cistern  should  not  open 
into  a  soil-pipe  or  sewer-pipe  or  drain,  but  always  into  the 
open  air,  since  water  is  so  prone  to  take  up  the  various 
kinds  of  gas  with  which  it  comes  in  contact,  and  the 
sewer-air  might  readily  contaminate  the  entire  contents  of 
the  cistern. 

Rain-water  is  especially  valuable  in  cooking  and  wash- 
ing, on  account  of  its  softness,  water  being  called  "  hard" 
when  it  contains  an  excess  of  the  salts  of  calcium  or  mag- 
nesium in  solution.  Hardness  due  to  the  presence  of 
calcium  bicarbonate  is  said  to  be  temporary,  because  it  is 
removed  when  the  water  is  boiled,  one  molecule  of  car- 
bonic acid  being  driven  off  by  the  heat,  leaving  the  insol- 
uble calcium  carbonate  behind.  Hardness  due  to  the  other 
salts  of  calcium  and  magnesium  is  called  permanent,  be- 
cause it  is  not  lost  by  boiling.  In  cooking  with  water 
temporarily  hard,  the  chalk  is  precipitated  upon  the  sides 
and  bottom  of  the  vessel  and,  being  a  non-conductor, 
prevents  the  passage  of  heat,  and  thus  wastes  fuel. 

Hard  water  may  also  prevent  the  proper  softening  of 
certain  foods,  such  as  peas  and  beans,  in  cooking.  In 
washing  and  laundry  work,  the  calcium  and  magnesium 
salts  unite  with  the  fatty  acids  of  the  soap  and  prevent 
the  formation  of  a  lather;  for  instance,  one  grain  of  chalk 
wastes  about  eight  grains  of  soap.  As  we  do  not  call  a 
water  hard  unless  it  contains  more  than  ten  grains  of 
chalk  or  its  equivalent  per  gallon,  and  as  rain-water  rarely 
has  more  than  one-half  a  grain  per  gallon,  it  is  easily 
understood  why  the  latter  is  so  valuable  in  the  kitchen 
and  laundry. 

A  water-supply  taken  from  rivers  or  smaller  streams 
not  polluted  by  the  refuse  and  sewage  from  towns,  fac- 


WATER.  133 

tories,  or  cultivated  farm  lands  higher  np  the  stream,  may 
be  fairly  pure  and  safe  to  use.  The  best  water  of  this 
kind  will  be  from  hilly  and  uninhabited,  uncultivated 
tracts,  with  many  small  streams  fed  by  constant  springs 
and  uniting  to  form  rapid  creeks  and  rivers.  Such  water 
may  be  tinged  slightly  with  vegetable  or  mineral  matters, 
but,  in  general,  such  coloration  is  harmless.  For  storage, 
dams  may  be  thrown  across  convenient  valleys,  thus  im- 
pounding the  water  and  at  the  same  time  keeping  it 
exposed  to  the  oxidizing  and  aerating  influence  of  the 
atmosphere,  and  allowing  the  solid  impurities  to  settle  to 
the  bottom.  Small  lakes  or  ponds  may  be  used  to  add  to 
supplies  of  this  kind,  provided  they  be  not  stagnant  nor 
have  much  decaying  matter  along  their  banks. 

On  the  other  hand,  water  from  a  stream  which  has 
received  the  sewage  from  a  village  or  town  of  any  size, 
or  the  refuse  of  factories,  or  the  drainage  from  large  tracts 
of  cultivated  land,  should  be  considered  as  at  least  suspi- 
cious. Hi  ver- waters  are  generally  hard,  and  may  contain 
any  of  the  minerals  in  the  soils  which  they  drain  or  over 
which  they  pass;  but  the  great  danger  is  from  impurities 
of  animal  origin  poured  into  them  along  their  course.  It 
is  not  safe  to  depend  altogether  on  the  self-purification  of 
sewage-contaminated  rivers,  as  was  formerly  done,  though 
much  of  the  sewage  and  filth  undoubtedly  is  removed, 
part  by  oxidation  by  the  air  in  the  water,  especially  in 
streams  flowing  over  dams,  rapids,  etc.,  part  by  subsidence 
or  deposition  along  the  banks,  part  by  fish  and  animal- 
culse,  and  much  by  the  myria .  s  of  the  saprophytic  bacte- 
ria which  such  waters  contain.  If  no  additional  pollution 
is  added,  what  is  left  unchanged  by  the  above  purifying 
agencies  is  still  further  diluted  by  the  supplies  of  pure 
water  that  every  stream  receives  from  springs  along  its 


134    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

banks  and  in  its  bed,  and  from  tributary  streamlets,  so 
that,  though  the  water  may  never  be  as  pure  as  it  was 
originally,  it  may  become  or,  by  proper  filtration  or  treat- 
ment, be  made  a  safe  and  usable  water.  But  where  the 
proportion  of  filth  exceeds  a  certain  percentage,  or  where 
sewage  is  being  constantly  added,  the  contained  oxygen  is 
rapidly  used  up  and  oxidation  ceases,  fish  and  animalculse 
cannot  live  in  the  water  for  lack  of  sufficient  oxygen,  and 
though  the  heavier  .and  larger  particles  of  the  sewage  sink 
to  the  bottom  or  stick  to  the  sides,  they  are  stirred  up  and 
set  in  motion  by  any  increase  in  the  velocity  of  the  cur- 
rent. The  only  remaining  agents  active  in  the  destruc- 
tion of  the  foul  matter  are  the  bacteria,  and  in  themselves 
they  are  often  insufficient  for  the  task,  and  the  water  thus 
polluted  is  entirely  unsafe  for  use. 

The  greatest  danger  from  sewage  contamination,  how- 
ever, is  that  it  may  at  any  time  add  the  germs  of  conta- 
gious disease  to  the  water,  which,  multiplying  rapidly,  and 
not  being  surely  removed  or  destroyed  by  the  ordinary 
methods  of  water-purification,  greatly  increase  the  risks 
to  health  from  its  use.  It  often,  fortunately,  happens 
that,  owing  to  the  hostility  of  the  saprophytic  bacteria 
of  the  water,  or  to  the  presence  of  certain  chemical  sub- 
stances, or  to  other  fortunate  conditions,  as  of  temper- 
ature and  the  like,  these  pathogenic  organisms  do  not 
multiply  as  rapidly  as  they  otherwise  would,  and  are, 
therefore,  not  as  plentiful  as  one  might  suppose;  but  as  it 
never  can  be  certainly  told  when  a  water  so  contaminated 
becomes  safe  for  use  again,  and  as  the  population  of  most 
towns  and  their  consequent  sewage  production  is  constantly 
increasing,  while  the  quantity  of  water  in  the  receiving 
stream  remains  about  the  same,  or  is  diminishing  from  year 
to  year,  the  use  of  such  water  should  be  avoided  if  possible. 


WATER.  135 

Water  from  large  fresh-water  lakes  will  be  of  the  best 
quality,  provided  it  be  taken  from  a  point  sufficiently  dis- 
tant from  the  shore  to  escape  all  danger  of  sewage  con- 
tamination. Chicago  has  apparently  lowered  the  mortality 
percentage  from  typhoid  fever  from  7.2  in  1891  to  2.1  in 
1895,  and  3.2  in  1896,  by  preventing  as  far  as  possible  the 
discharge  of  sewage  into  Lake  Michigan,  and  by  taking 
the  water-supply  from  the  lake  at  a  minimum  distance 
of  one  mile  instead  of  1400  feet  from  shore  as  formerly. 
Water  from  small  lakes  or  ponds,  and  even  from  storage 
reservoirs,  may  become  offensive  to  taste  and  smell  through 
the  growth  in  them  of  minute  vegetable  organisms,  such  as 
the  algae,  though  it  is  not  known  that  these  are  prejudicial 
to  health. 

Ordinarily,  water  loses  m  uch  organic  matter  as  it  perco- 
lates through  the  soil,  but  takes  up  considerable  carbonic 
acid  from  the  soil-air,  which  increases  its  solvent  powers 
so  that  it  may  take  up  some  of  the  mineral  constituents  of 
the  soil  through  which  it  passes.  When  these  mineral 
substances  become  so  great  in  amount  as  to  give  the  water 
a  decided  taste  or  medicinal  properties,  we  call  it  a  min- 
eral water;  but  when  the  inorganic  matter  does  not  render 
it  objectionable  to  the  taste  or  too  hard,  the  water,  whether 
subsoil  or  artesian,  will  usually  be  considered  to  be  quite 
pure. 

Attention  has  already  been  called  to  the  pollution  of 
the  soil.  How  then  can  the  water  in  passing  through  it 
lose  its  organic  contents  and  become  pure  ?  Partly  by 
mechanical  filtration,  but  mainly  through  the  combined 
action  of  the  saprophytic  bacteria  and  the  oxygen  of  the 
soil-air,  which  rapidly  convert  the  organic  impurities, 
both  suspended  and  dissolved,  into  simpler  and  harmless 
end-products.  The  substances  of  vegetable  nature  are 


136    -4  MANUAL  OF  HYGIENE  AND  SANITATION. 

ultimately  resolved  by  these  agencies  into  carbonic  acid, 
water,  etc.,  while  those  of  animal  origin  and  containing 
nitrogen,  give  rise  to  the  various  ammonia  compounds,  or 
may  be  further  oxidized  into  nitrous  and  nitric  acids  and 
their  salts,  all  entirely  harmless  in  the  proportions  in  which 
they  are  found  in  the  percolating  ground-water. 

The  subsoil-water  sinks  through  the  ground  till  at  some 
level  or  other  it  reaches  an  impermeable  stratum,  where  it 
is  retained  in  natural  basins  or  escapes  at  some  outcropping 
of  the  stratum  below  the  water-level,  thus  forming  a  spring. 
The  level  of  the  water  in  these  underground  reservoirs 
is  constantly  changing,  according  to  the  season,  rainfall, 
discharge  from  springs,  etc.,  though  the  variation  for  any 
given  place  is  usually  regular,  and  differs  little  from  year 
to  year.  It  is  from  wells  sunk  to  these  water-bearing 
strata  and  from  springs  that  the  majority  of  people  who 
do  not  live  in  towns  or  cities  supplied  by  water-works  obtain 
their  supply.  These  underground  bodies  of  water  are  con- 
stantly moving  toward  outlets  at  some  point  or  another, 
but  the  current  is  not  rapid,  owing  to  the  friction  and 
capillary  force  of  the  particles  of  soil  through  which  it 
passes.  For  the  same  reason  the  surface  of  the  water  is 
not  horizontal,  but  curved,  the  curve  being  sharpest  near 
the  outlet;  and  the  difference  in  level  between  high  and 
low  water  will  be  least  near  the  outlet;  also,  the  higher 
the  level  the  greater  the  fall  to  the  outlet,  and  the  greater 
the  discharge. 

The  above  remarks  regarding  the  purity  of  this  under- 
ground water  do  not  hold  good  for  water  from  ordinary 
shallow  wells,  under  fifty  feet  in  depth,  and  which  do  not 
pass  through  an  impermeable  stratum,  nor  where  the 
water  passes  almost  directly  from  surface  to  outlet,  for  in 
both  cases  the  complete  filtering  action  of  the  soil  and  the 


WATER.  137 

removal  of  organic  matter  by  the  prolonged  action  of  the 
saprophytic  bacteria  are  wanting.  Owing  to  the  lessening 
of  lateral  resistance  the  surface- water  passes  almost  directly 
into  the  well  (unless  the  wall  of  the  latter  be  made  water- 
tight to  almost  the  full  depth),  and  may  carry  with  it 
solutions  of  all  the  impurities  polluting  the  soil  about  the 
well;  and  as  wells  drain  a  very  considerable  area — Parke 
says  one,  in  ordinary  soils,  whose  radius  is  equal  to  four 
times  the  depth  of  the  well — there  are  few  wells  about 
which  such  an  area  is  not  subject  to  dangerous  pollution. 
Moreover,  the  influence  of  pumping  or  other  sudden  with- 
drawal of  water  from  the  well  is  even  more  important, 
since  it  extends  a  distance  from  fifteen  to  one  hundred 
and  sixty  times  the  temporary  depression  of  the  water- 
level,  and  impurities  may  thus  be  drawn  into  the  well 
which  would  ordinarily  tend  to  flow  away  from  it. 

Especially  about  human  dwellings,  where  wells  are  com- 
monly located,  is  filth  apt  to  be  carried  into  the  well,  for 
sewage  and  dirt  of  almost  every  kind  is  constantly  increas- 
ing in  quantity  in  the  soil  about  a  house,  with  the  ever- 
present  danger  of  it  also  receiving  the  specific  germs  of 
disease. 

Only  such  parts  of  this  pollution  as  can  be  dissolved 
may  reach  the  water  in  the  well,  together  with  the  bacteria 
which  pass  freely  through  almost  all  soils  when  resistance 
to  the  water  current  is  so  markedly  diminished  ;  and  it  is 
a  strange  fact  that  many  waters  thus  polluted  are  spark- 
ling and  clear,  with  a  pleasant  taste  and  no  bad  odor,  so 
that  all  suspicion  as  to  their  true  character  may  be  want- 
ing. Moreover,  there  is  always  danger  that  this  contami- 
nation may  become  so  concentrated  as  to  produce  very 
serious  results,  even  though  specific  disease  germs  be 
absent,  and  this  may  occur  in  various  ways:  (a)  The  well 


138 


MANUAL  OF  HYGIENE  AND  SANITATION. 


may  be  so  deep  or  the  character  of  the  soil  such  that  in 
ordinary  weather  the  liquid  passing  through  the  soil  is  so 
purified  that  it  gives  no  bad  properties  to  the  water;  but 
if  the  soil  is  being  continually  infiltrated  with  dangerous 
imparities,  and  if  at  last  heavy  rains  or  continued  wet 
weather  supervene,  there  may  be  more  and  more  of  these 


Depression  of  water  in  shallow  well  by  pumping.    A,  well ;  B,  cesspool ;   C, 
underground  water  curve.    (After  FIELD  and  PEGGS.) 

impurities  dissolved  and  carried  into  the  well  until  the  pro- 
portion of  harmful  matter  in  the  water  passes  the  safety 
line,  and  we  have  marked  illness  or  increased  predisposi- 
tion to  disease  among  those  using  the  water  as  a  result;  or 
(6)  in  continued  dry  weather  the  ground-water  may  be 
lowered  to  such  an  extent  that  the  impurities  that  were 
formerly  well  diluted  become  concentrated  and  dangerous 
enough  to  cause  sickness,  even  though  there  be  no  unusual 
pollution  of  the  soil  about  the  well ;  or  (c)  the  water-level 
in  the  well  being  suddenly  or  persistently  lowered,  a 
greater  area  is  drained  and  additional  collections  of  sewage 
may  empty  into  the  well.  (Fig.  24.) 

Deep  wells  are  those  over  fifty  feet  in  depth,  or  which 


WATER.  139 

go  through  an  impermeable  stratum,  and  do  not  get  their 
supply  from  the  subsoil-water.  Artesian  wells  are  very 
deep  wells,  piercing  one  or  more  impermeable  strata. 

Sometimes  the  water  rises  and  flows  out  of  the  mouth, 
in  which  case  the  well  draws  its  supply  from  a  water- 
bearing stratum  between  two  impermeable  ones,  and  which 
has  its  only  outcroppings  higher  than  the  top  of  the  well. 
The  water  accumulates  in  this  natural  reservoir  above  the 
level  of  the  well-mouth,  and  is  forced  out  as  soon  as  the 
opening  pierces  the  uppermost  impermeable  stratum.  It 
is  apt  to  be  of  much  better  quality  than  that  from  shallow 
wells,  since  it  usually  represents  the  total  percolation 
through  an  extent  of  ground  surface  in  comparison  to 
which  the  combined  areas  of  pollution  within  its  limits 
are  insignificant,  the  percentage  of  impurities  in  the  water 
being  consequently  reduced  by  dilution  to  much  below  the 
danger  point.  It  is  for  the  same  reason  that  there  is  such 
a  difference  in  the  quality  of  spring-water  and  that  from 
most  shallow  wells.  Though  they  seem  to  have  a  common 
source,  one  is  the  composite  water  of  a  large  district,  of 
which  the  average  impurity  or  contamination  per  unit  of 
surface  may  be  infinitesimal;  the  other  is  the  special  per- 
colate from  a  limited  area  which  is,  for  the  reasons  given, 
particularly  liable  to  be  highly  and  dangerously  polluted. 

Artesian  or  deep-well  water  will  also  likely  be  very  free 
from  organic  matters,  but  possibly  heavily  charged  with 
mineral  salts.  Should  these  latter  not  be  present,  the 
water  will  probably  be  of  excellent  quality,  though  if  the 
well  be  very  deep,  it  may  be  too  warm  for  immediate  use 
as  a  potable  water. 

Frequently  well-water,  and  that  most  often  from  shal- 
low wells,  is  the  only  kind  available,  especially  in  country 
districts.  In  such  cases  care  must  be  taken  that  impuri- 


140    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

ties  are  kept  out  of  the  well  by  all  possible  means,  and  if 
this  be  done,  water  may  often  be  had  of  safe  and  excellent 
quality.  The  area  about  all  wells  should  be  kept  clean 
and  the  sources  of  all  possible  contamination  removed. 
Wells  should  be  walled  or  cased,  shallow  wells  to  the 
water-level,  and  deep  wells  to  the  first  impermeable 
stratum  if  possible,  in  order  to  cause  the  water  to  perco- 
late through  as  much  soil  as  possible  before  entering  the 
well.  Wells  should  also  have  a  good  curb  to  keep  out 
splashings  and  drippings  of  muddy  or  dirty  water. 

The  well  should  be  as  far  as  possible  from  any  source 
of  contamination,  especially  if  the  latter  be  a  constant  one. 
We  must  not  forget  that  wells  drain  a  large  area.  As  the 
ground-water  has  a  constant  movement  in  the  direction  of 
natural  outlets,  the  well  should  be  so  located  that  the  cur- 
rent flows  jrom  it  toward  any  near-by  cesspool  or  other 
source  of  pollution.  The  direction  of  the  underground 
current  can  generally  be  determined  by  noting  the  loca- 
tion of  the  nearest  spring  or  water-course,  by  observing 
the  dip  of  the  underlying  strata,  or  by  digging  holes  about 
the  well  and  dissolving  salt  or  an  aniline  dye  in  them  in 
turn  and  testing  the  water  from  the  well  after  a  time  for 
the  salt  or  color.  If  a  well  be  much  deeper  than  a  neigh- 
boring cesspool,  it  may  drain  from  the  latter,  even  against 
the  ground-water  current,  especially  if  the  water  in  the 
well  be  suddenly  lowered.  Again,  dangerous  impurities 
have  sometimes  been  carried  into  wells  from  long  distances 
through  fissures  or  crevices  in  the  rock. 

The  water  from  the  well  should  be  frequently  tested  for 
chlorides  and  nitrates,  these  indicating  sewage  contamina- 
tion, and  this  should  be  done  especially  after  heavy  rains 
and  also  when  the  water  in  the  well  becomes  low.  The 
taste  and  odor  of  the  water  should  also  be  noted  after 


WATER.  141 

standing  or  being  heated.  Some  other  source  should  be 
sought  whenever  the  tests  show  contamination,  or  when 
there  are  cases  of  infectious  disease  near  at  hand.  Boil- 
ing the  water  and  filtration  are  always  to  be  recommended. 

Wells  in  thickly  settled  towns  should  not  be  used  to 
supply  drinking-  or  cooking-water,  as  the  soil  is  always 
more  or  less  saturated  with  filth  and  sewage,  and  it  is  prac- 
tically impossible  in  such  places  to  locate  a  well  which 
will  not  be  in  constant  danger  of  receiving  harmful  im- 
purities. 

The  decision  as  to  the  quality  of  any  water  must  in 
each  case  be  determined  by  all  the  circumstances  available 
which  relate  to  it,  and  these  should  all  be  thoroughly 
investigated  before  rendering  an  opinion,  as  some  of  them 
may  counteract  the  others.  However,  other  things  being 
equal,  the  value  of  a  water  will  probably  be  in  accord 
with  the  following  table: 

f  1.  Spring- water,  |  Very 
Wholesome  \  2.  Deep  well-water,  palatable. 

v.  3.  Water  from  unpolluted  streams,  I  Moderately 
Suspicious    /  4.  Stored  rain-water,  palatable. 

<.  5.  Surface-water  from  cultivated  land,  ~| 

Dangerous    {  6-  Sewage-polluted  river-water,  j-  palatable. 

I  7.  Shallow  well- water. 

A  good  potable  water  should  be  perfectly  clear,  free  from 
odor  or  taste,  cool,  well  aerated,  and,  if  possible,  soft,  or 
with  only  a  mild  degree  of  hardness.  Circumstances  must 
determine  the  amount  of  dissolved  matters  permissible; 
what  is  an  excess  in  one  case  might  not  be  so  in  another. 

We  may  also  classify  waters  as  follows  :  1.  Pure  and 
wholesome  water.  2.  Usable  water.  3.  Suspicious  water. 
4.  Dangerous  water.  (See  table  on  page  179;)  Pure  waters 
and  usable  waters  may  be  used  without  filtration;  those 
of  the  third  class  should  be  filtered  before  distribution, 
and  also  at  the  house  before  use,  if  possible,  and  a  purer 


142    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

source  sought  out  or  all  sewage-pollution  prevented. 
Those  of  the  fourth  class  should  not  be  used  at  all  except 
when  it  is  absolutely  unavoidable,  and  then  only  after 
purification  by  all  the  means  at  command. 

Inasmuch  as  most  large  cities  must  from  necessity  fur- 
nish a  water  of  the  second  or  third,  and  occasionally  even  of 
the  fourth  class,  such  water  should  be  purified  as  much  as 
possible  before  distribution,  by  storage  for  a  time  in  settling 
reservoirs  and  by  some  effective  system  of  filtration,  com- 
bined with  chemical  treatment,  if  necessary.  As  much  of 
the  organic  matter  is  oxidized,  and  many  of  the  patho- 
genic bacteria  are  destroyed  by  saprophytes  and  other 
causes  while  the  water  is  standing  in  the  settling-reser- 
voirs, a  water  originally  suspicious  or  worse  may  often  be 
made  quite  usable  by  the  above  means  properly  employed. 
Not  only  must  the  storage  reservoirs  and  filtering  appa- 
ratus be  kept  clean,  but  care  must  be  had  that  the  dis- 
tributing apparatus  does  not  allow  soil-  or  sewer-air  or 
sewage  to  be  drawn  in  through  leaks  in  the  mains  at 
times  when  the  flow  is  intermittent,  and  that  lead  pipes 
are  not  used  in  the  houses  if  the  character  of  the  water  is 
such  that  it  acts  on  that  metal. 

Diseases  Caused  by  Impure  Drinking-water.  A 
polluted  water  may  carry  the  organisms  of  infectious  dis- 
eases, or  it  may  produce  or  favor  the  development  of 
diseases  which  are  not  due  to  specific  germs.  In  addition 
to  this,  and  of  at  least  equal  importance  from  a  sanitary 
point  of  view,  is  the  depressed  state  of  the  system  that  the 
habitual  use  of  impure  drinking-water  causes,  and  the 
predisposition  to  disease  that  ensues.  By  the  power  of 
accommodation  and  through  long  habit,  a  community  may 
become  so  protected  against  an  impure  water  as  to  mani- 
fest no  striking  symptoms,  while  strangers  may  be  seri- 


WATER.  143 

ously  affected  by  it;  but  even  in  such  a  case,  the  condition 
of  those  habitually  using  the  water  will  be  apt  to  be 
depressed  and  far  from  good. 

The  non- infectious  diseases  likely  to  be  caused  by  im- 
purities in  the  drinking-water  are  primarily  those  affecting 
the  alimentary  tract,  as  dyspepsias,  diarrhoeas,  and  other 
disturbances  having  their  origin  in  severe  gastric  or  intes- 
tinal irritation.  So,  also,  impure  water,  even  though  it 
do  not  contain  the  actual  germs,  may  have  much  to  do 
in  bringing  on  an  attack  of  specific  dysentery  by  so  irri- 
tating the  lower  intestine  as  to  make  it  especially  receptive 
to  the  cause  of  the  disease  when  introduced  from  another 
source. 

Large  quantities  of  the  sulphates  of  calcium  and  mag- 
nesium are  thought  to  have  special  influence  in  causing 
dyspepsias,  with  loss  of  appetite,  pain  at  epigastrium,  etc. 
An  excess  of  iron  in  water  is  also  prone  to  produce  con- 
stipation, headache,  loss  of  appetite,  and  malaise.  Goitre 
and  the  formation  of  vesical  calculi  are  each  supposed  to 
be  due  to  mineral  or  inorganic  impurities,  though  the  true 
relation  of  impure  drinking-water  to  these  diseases  is  still 
unsettled.  "  It  has  long  been  a  popular  opinion  that 
drinking  lime-waters  gives  rise  to  calculi  of  the  oxalate 
and  phosphate  of  calcium/'  and  the  "  opinion  that  impure 
water  is  the  cause  of  goitre  is  as  old  as  Hippocrates  and 
Aristotle."  Further  study  of  the  principles  underlying 
the  new  treatment  of  goitre  with  glandular  extracts  may 
make  it  easier  to  determine  whether  bad  water  has  or  has 
not  a  causative  influence  in  the  .production  of  the  disease. 

Diarrhoea  may  be  produced  by  any  of  the  following 
impurities  in  water:  Suspended  substances  of  any  kind, 
but  especially  those  of  fecal  origin;  dissolved  animal, 
vegetable,  or  mineral  matters,  and  fetid  gases.  The  diar- 


144    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

rhoea  produced  by  any  of  these  contaminants  may  be  so 
severe  as  to  simulate  true  dysentery  and  cause  doubt  as  to 
the  diagnosis. 

Certain,  metals  may  be  taken  up  from  the  earth's  strata, 
or  from  the  lining  of  cisterns,  and  may  produce  their  char- 
acteristic and  poisonous  symptoms  in  the  system.  Lead  is 
one  of  these  metals,  and  it  will  be  well  to  note  here  the 
waters  that  are  especially  apt  to  take  up  this  metal.  Pure 
waters  and  those  containing  much  oxygen  act  most  power- 
fully on  lead,  as  do  those  containing  organic  nitrates  and 
nitrites,  especially  ammonium  nitrate.  Waters  containing 
carbonic  acid  and  the  salts  of  lime  and  magnesia  and 
those  free  of  absorbed  gases  act  least  on  lead,  and  car- 
bonic acid  seems  even  to  protect  lead  by  forming  an  insolu- 
ble carbonate  on  its  surface.  Lead  is  mote  easily  dissolved 
if  other  metals  are  in  contact  with  it,  probably  owing  to 
electrolytic  action.  Lead  should  not  be  used  for  pipes 
nor  to  line  cisterns  unless  suitable  tests  show  that  the 
water  does  not  affect  them,  nor  should  any  water  be  used 
in  which  the  tests  show  more  than  one-twentienth  of  a 
grain  of  lead  per  gallon.  Even  water  containing  carbonic 
acid  may  take  up  lead  for  a  time  from  new  pipes  until  the 
insoluble  carbonate  is  formed  within  them. 

Of  the  infectious  diseases,  germs  of  typhoid  fever, 
cholera,  dysentery,  and  malaria  are  usually  carried  into 
the  system  by  the  drinking-water,  while  the  same  is  often 
true  of  yellow  fever,  scarlet  fever,  diphtheria,  and  kin- 
dred diseases.  But,  as  with  the  impurities  causing  non- 
infectious  diseases,  water  containing  disease  germs  may 
sometimes  be  used  for  a  long  time  by  those  accustomed  to 
it  without  the  development  of  the  specific  malady,  and  it 
may  only  be  after  the  system  is  weakened  by  excesses  or 
other  predisposing  conditions  that  the  diesase  manifests 


WATER.  145 

itself;  or  it  may  happen  that  only  strangers  and  non- 
acclimated  inhabitants  incur  the  disease.  It  has  been  sug- 
gested that  this  immunity  is  probably  brought  about  by 
the  very  gradual  introduction  into  the  body  of  the  disease 
germs  and  their  poisons,  so  that  old  residents  are  not 
susceptible  to  the  quantities  of  either  of  these  which  are 
sufficient  to  give  rise  to  the  particular  diseases  in  new- 
comers. 

Many  instances  have  been  recorded  which  practically 
prove  the  transmissibility  of  infectious  diseases  by  means 
of  drinking-water,  and  of  these  reference  may  be  made  to 
the  epidemics  of  typhoid  fever  at  Lausen,1  in  Switzerland, 
and  at  Plymouth,  Pa.  ;2  of  malaria  on  board  the  transport 
ship  "Argo";3  and  of  cholera  in  London.4  The  writer 
himself  had  an  opportunity  of  investigating  an  epidemic 
of  typhoid  fever  in  a  small  village  in  North  Carolina.5 
In  this  there  were  only  four  or  five  in  about  sixty  cases 
which  were  not  undoubtedly  due  to  the  contamination  of 
the  subsoil-water  by  the  infected  excreta  from  the  first 
case;  and  of  four  exceptions,  which  were  all  in  one  family, 
the  first  was  in  all  probability  infected  while  in  attendance 
upon  sick  neighbors.  It  was  also  shown  that  with  the 
exception  of  these  four,  the  cases  all  developed  directly 
along  the  lines  of  natural  drainage  leading  from  the  resi- 
dence of  the  original  case — a  boy,  who  came  to  the  village 
sick  with  the  disease — and  that  the  latest  cases  to  develop 
were  those  most  remote  from  the  starting  point  of  the 
infection. 

Moreover,    in   most   large  cities  of    this   country  the 

1  Pepper's  System  of  Medicine,  vol.  i.  p.  250. 

2  Robe's  Text-book  of  Hygiene,  2d  edition,  p.  63. 

s  Parke's  Hygiene,  8th  edition,  p.  64,  and  Rone,  p.  60. 

*  Rone,  p.  64.  s  University  Medical  Magazine,  May,  1892. 

10 


146    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

typhoid  fever  death-rate  is  accepted  as  the  direct  index 
of  the  character  of  the  water-supply;  and  it  seems  to  be 
a  fact  almost  without  exception,  that  any  marked  improve- 
ment in  the  latter  will  be  followed  by  an  immediate  and 
positive  reduction  in  the  former.  The  same  may  also  be 
said  to  hold  good  in  regard  to  diarrhoeal  diseases,  while  in 
eastern  North  Carolina  there  has  been  a  very  marked 
reduction  in  the  prevalence  of  malarial  fevers  as  a  result 
of  the  efforts  of  the  State  Board  of  Health  to  persuade 
the  people  to  substitute  rain-  or  deep  well-water  for  the 
subsoil-water,  which  was  almost  universally  used  a  few 
years  ago. 

The  ova  of  certain  parasites,  such  as  tape-  or  round- 
worms,  may  often  be  taken  into  the  system  with  the 
drinking-water,  and  these  upon  developing  may  cause 
disturbances  more  serious  than  the  slight  attention  usually 
given  to  them  would  seem  to  indicate.  Any  attack  of 
convulsions  in  a  child  or  other  manifestation  of  severe 
reflex  action  should  lead  to  the  inquiry  as  to  whether 
these  parasites  may  not  be  present  and  whether  the  water- 
supply  has  not  been  a  source  of  invasion. 

Regarding  the  foregoing  remarks,  Parkes  makes  the 
following  statements  :  "  1.  An  epidemic  of  diarrhoea  in  a 
community  is  almost  always  owing  to  either  impure  air, 
impure  water,  or  bad  food.  If  it  affects  a  number  of  per- 
sons suddenly,  it  is  probably  owing  to  one  of  the  last  two 
causes,  and  if  it  extends  over  many  families,  almost  cer- 
tainly to  water.  But  as  the  cause  of  the  impurity  may 
be  transient,  it  is  not  easy  to  find  experimental  proof. 
2.  Diarrhoea  or  dysentery  constantly  affecting  a  commu- 
nity, or  returning  periodically  at  certain  times  of  the  year, 
is  far  more  likely  to  be  produced  by  bad  water  than  by 
any  other  cause.  3.  A  very  sudden  and  localized  out- 


WATER.  147 

break  of  typhoid  fever  or  cholera  is  almost  certainly  owing 
to  the  introduction  of  the  poison  by  water.  4.  The  same 
fact  holds  good  in  malarial  fevers,  and,  especially  if  the 
cases  are  very  grave,  a  possible  introduction  by  water 
should  be  inquired  into.  5.  The  introduction  of  the  ova 
of  certain  entozoa  by  means  of  water  is  proved  in  some 
places,  probable  in  others.  6.  Although  it  is  not  at 
present  possible  to  assign  to  every  impurity  in  water  its 
exact  share  in  the  production  of  disease,  or  to  prove  the 
precise  influence  on  public  health  of  water  which  is  not 
extremely  impure,  it  appears  certain  that  the  health  of  a 
community  always  improves  when  an  abundant  and  pure 
water-supply  is  given;  and,  apart  from  this  actual  evi- 
dence, we  are  entitled  to  conclude  from  other  considera- 
tions that  abundant  and  good  water  is  a  prime  sanitary 
necessity. J '  The  statistics  already  given  and  those  to  come 
in  later  pages  are  confirmatory  of  the  correctness  of  this 
last  assertion ;  and  sanitary  authorities  now  realize  that  the 
main  cause  of  an  increase  in  the  death-rate  of  diarrhoeal 
diseases  is  more  often  to  be  fairly  attributed  to  a  bad  water- 
supply  than  to  improper  food  or  untoward  temperatures. 
Even  with  respect  to  cholera  infantum  (which  is  generally 
supposed  to  be  principally  due  to  the  influence  of  exces- 
sive heat  upon  the  infant  .and  its  food),  a  number  of  epi- 
demics show  a  closer  relation  to  impure  water-supply  than 
to  temperature  changes. 

The  Purification  of  Water.  Impurities  in  water  may 
be  either  solid  matters  in  suspension,  or  dissolved  sub- 
stances, and  may  be  organic  or  inorganic.  Any  turbidity 
is  due  to  solid  particles,  and  water  free  from  these  is  clear, 
though  it  may  have  a  color  more  or  less  deep  from  dis- 
solved matters.  Moreover,  a  clear  water  may  contain  such 
solid  bodies  as  bacteria,  ova  of  parasites,  etc.,  which  are  too 


148    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

minute  to  be  seen  with  the  naked  eye.  "Whether  harmful 
or  not,  all  impurities  should  be  removed  in  so  far  as  is  pos- 
sible from  all  supplies  of  drinking-water.  This  may  be 
done  to  a  considerable  extent  with  large  volumes  of  water 
before  it  is  distributed  to  consumers,  and  should  always  be 
attended  to  by  the  latter  if  the  water  is  not  already  clean 
and  within  the  limits  of  safety  when  they  receive  it.  In 
fact,  a  large  city  at  the  present  time  can  scarcely  have  a 
more  important  subject  for  consideration  than  that  of 
obtaining  the  purest  possible  water-supply  for  its  people. 
There  is  always  a  tendency  among  many  to  allow  matters 
to  continue  as  they  are,  or  as  they  have  been  in  the  past; 
and  a  decided  objection  by  others  to  incurring  additional 
expense  for  what  may  seem  to  them  only  aesthetic  reasons; 
but,  no  matter  what  may  be  the  cost  of  providing  a  reason- 
able supply  of  pure  water  for  any  large  city's  personal  and 
domestic  uses,  a  very  little  consideration  will  show  that 
such  expenditure  is  true  economy  from  solely  a  financial 
point  of  view,  even  though  we  ignore  the  misery  and  sor- 
row of  the  sickness  and  deaths  that  are  due  to  the  use  of 
a  polluted  water. 

As  has  been  stated  by  the  excellent  authority  quoted 
above,  "  the  health  of  a  community  always  improves 
when  an  abundant  and  pure  water-supply  is  given.77 
"  The  death  of  3400  persons  from  cholera  followed  the 
temporary  supply  of  unfiltered  water  by  the  East  London 
Water  Company  in  1866,  while  the  rest  of  London  remained 
nearly  free  from  the  disease,77  and  in  1892  "  Hamburg 
lost  8605  citizens  from  the  same  disease  alone,77  regarding 
which  "  the  health  authorities  found  that  the  principal 
cause  of  this  epidemic  was  the  polluted  water-supply.77 

i  Hazen :  The  Filtration  of  Public  Water  Supplies,  1895. 


WATER.  149 

Again,  after  the  scourge  of  typhoid  fever  in  Plymouth, 
Pennsylvania,  in  1885,  when  there  were  1104  cases  and 
1 14  deaths  within  a  few  weeks  in  a  population  of  8000,  as 
a  result  of  the  pollution  of  the  water-supply  by  a  single 
person,  great  care  was  taken  to  determine  the  exact  cost  of 
the  "  visitation/7  as  some  would  term  it.  It  was  found 
that  the  actual  expenditure  for  the  care  of  the  sick  was 
$67,100.17;  for  loss  of  wages  by  those  recovering,  $30,- 
020.08;  a  total  of  $97,120.25,  to  which  should  be  added 
a  number  of  times  the  $18,419.52  that  those  who  died 
were  earning  per  annum  when  taken  sick.  How  much 
cheaper  in  comparison  would  a  protecting  filter-plant  have 
been  !  But  overlooking  special  epidemics,  and  considering 
the  average  annual  typhoid  death-rates  of  our  cities,  we 
find  that  experience  both  here  and  abroad  shows  that 
with  a  pure  water-supply  a  fair  death-rate  from  this  dis- 
ease is  25  per  100,000,  and  that  any  city  may  reasonably 
expect  to  secure  such  a  rate  by  observing  proper  precau- 
tions. And  yet  only  eight  cities  of  over  50,000  popula- 
tion whose  mortality  returns  were  given  in  the  United 
States  Census  Reports  of  1890  had  so  low  a  figure.  On 
the  other  hand,  there  were  five  cities  of  over  (and  two  of 
less  than)  50,000  that  had  100  or  more  deaths  per  100,000, 
all  using  unfiltered  river-water.  The  remaining  forty-one 
of  those  above  50,000  had  rates  varying  from  26  to  98. 
Counting  each  death  as  a  loss  to  the  community  of  $5000 — 
not  an  excessive  estimate  according  to  the  finding  of  courts, 
and  since  most  typhoid  cases  occur  during  the  working  age 
of  from  fifteen  to  fifty  years — "  the  saving  due  to  filtration  " 
on  the  unnecessary  deaths  from  typhoid  fever  "  would 
have  paid  for  the  entire  cost  of  filters  in  the  first  year 
they  were  in  use"  in  the  first  seven  of  these  cities;  "  in 
sixteen  others,  with  an  aggregate  population  of  3,717,560, 


150    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

filtration  would  have  paid  for  itself  in  two  years  or  less/' 
and  in  "  eighteen  others  with  an  aggregate  of  3,238,617, 
filtration  would  have  saved  seven  or  more  lives  per  100,000 
annually,  and  would  have  more  than  paid  for  the  interest 
and  cost  of  operating  the  filters." 

Lawrence,  Mass.,  with  a  population  of  44,654  in  1890, 
built  a  filter  at  a  cost  of  $67,000,  and  saved  enough  lives, 
at  $5000  per  head,  to  pay  for  it  within  the  first  four 
months  that  it  was  in  use.  In  Chicago,  when  the  simi- 
larly estimated  loss  from  typhoid  deaths  in  the  city  and 
suburbs  amounted  to  over  $10,000,000  in  1891,  the  aban- 
doning of  a  shore  inlet  near  the  mouth  of  the  sewage  pol- 
luted Chicago  river  in  1892  resulted  in  a  reduction  of  60 
per  cent,  in  the  typhoid  mortality  during  the  following 
year.  Philadelphia  also  had  a  typhoid-fever  mortality 
rate  of  40  per  100,000  in  1895,  and  of  about  32  in  1896 
and  1897,  representing  a  preventable  death-loss,  as  above 
calculated,  of  from  $400,000  to  $850,000;  whereas  an 
extremely  competent  authority  has  estimated  (September, 
1896)  that  the  first  cost  of  installing  filters  with  all  neces- 
sary accessories  capable  of  giving  an  average  daily  supply 
of  100  gallons  and  a  maximum  of  150  gallons  per  capita 
for  the  whole  population  would  be  only  about  $3,000,000, 
and  that  the  annual  expense  for  operating  these  filters  would 
only  be  $166,000,  the  total  annual  outlay  on  the  whole 
capitalization  thus  being  actually  less  than  the  death-loss 
from  one  disease  for  one  year.  Nor  must  it  be  forgotten 
that  these  figures  do  not  include  the  cost  of  medical  atten- 
tion and  nursing,  nor  the  loss  of  time  and  employment  by 
those  that  recovered,  nor  do  they  consider  the  financial 
loss  due  to  sickness  and  deaths  from  other  diseases  than 
typhoid  fever  that  may  be  fairly  credited  to  polluted 
water-supplies.  Can  any  one  doubt  where  true  municipal 


WATER.  151 

economy  lies,  and  is  there  not  abundant  opportunity  for 
sanitary  education  and  work  in  this  direction  alone  for 
many  years  to  come  ? 

Purification  before  distribution  may  be  by  either  or  all 
of  three  methods:  subsidence,  chemical  treatment,  and 
-filtration. 

The  first  method  consists  in  allowing  the  water  to  stand  in 
large  reservoirs  till  the  greater  part  of  the  suspended  mat- 
ters have  fallen  to  the  bottom.  If  sufficient  time  be  given, 
much  of  the  organic  matter,  whether  solid  or  dissolved, 
will  be  decomposed  or  reduced  to  simpler  compounds  by 
the  action  of  the  sunlight,  oxygen,  animalcule,  sapro- 
phytes, etc.  Most  of  the  bacteria,  also,  especially  the 
pathogenic  species,  will  disappear  either  by  sedimentation 
or  by  death  from  lack  of  favorable  conditions.  Conse- 
quently, a  water  originally  quite  impure  may  be  much 
improved  by  this  method  alone,  while  if  it  is  used  in  con- 
junction with  and  preliminary  to  filtration,  it  will  be  addi- 
tionally advantageous,  in  that  it  reduces  the  cost  of  the 
latter  by  lessening  the  frequency  and  cost  of  cleaning  the 
filters. 

What  the  capacity  of  the  reservoirs  and  the  time  of 
storage  should  be  depends  on  circumstances.  If  it  is  the 
only  method  of  purification  employed,  and  especially  if 
the  water  is  very  foul,  the  longer  the  time  of  storage  the 
better.  Again,  if  the  source  of  supply  is  variable  in  out- 
put, or  if  it  is  liable  to  excessive  pollution  for  limited 
periods,  the  capacity  should  be  such,  if  possible,  that 
water  need  not  be  collected  during  the  emergency.  On 
the  other  hand,  if  the  water  is  to  be  subsequently  filtered, 
the  capacity  of  the  reservoirs  and  time  of  storage  need  not 
be  so  great.  Most  German  authorities  on  filtration  hold 
that  sedimentation  for  twenty-four  hours  or  even  less  is 


152    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

sufficient,  most  of  the  solid  matters  being  precipitated 
within  that  time,  if  at  all,  and  the  filters  being  relied  upon 
to  remove  the  remainder,  especially  the  finer  particles  and 
the  bacteria.  The  English  practice  is  to  store  the  water 
for  a  longer  time,  though  local  causes  related  to  the  source  of 
supply  are  the  reason  for  this.  Thus  the  Lea  and  Thames, 
from  which  "the  London  companies  take  much  of  their 
water,  are  subject  to  extra  pollution  in  times  of  flood, 
which  are  usually  of  short  duration,  and  a  sufficient  reserve 
for  such  periods  is  of  obvious  value. 

All  storage  reservoirs  should,  of  course,  be  kept  free 
from  extraneous  contamination  and  should  be  cleaned 
from  time  to  time.  Weeds  should  be  destroyed,  as  they 
sometimes  give  a  bad  taste  to  the  water.  The  water  may 
also  have  a  bad  taste  or  odor  from  algse  and  other  species 
of  minute  plants,  which  especially  favor  a  pure  water 
exposed  to  sunshine.  They  are  not  known  to  be  harmful, 
but  it  may  be  necessary  to  cover  the  reservoirs  to  get  rid 
of  them  and  their  unpleasant  properties. 

Where  a  water  is  very  hard  or  contains  an  excess  of 
mineral  matter,  it  is  frequently  of  advantage  to  treat  it 
chemically.  If  the  hardness  is  due  to  the  bicarbonate  of 
calcium  in  excess,  it  may  be  removed  by  the  addition  of 
a  solution  of  calcium  hydrate  to  the  water,  the  insoluble 
carbonate  of  calcium  being  formed  and  precipitated.  The 
change  is  represented  by  the  equation:  CaOCO2CO2  -|- 
Ca(HO)2  =  2CaCO3+H2O.  Clark' s  process,  based  on  this 
reaction,  is  as  follows:  About  fourteen  or  fifteen  hundred- 
weight of  lime  is  allowed  to  each  million  gallons  of  water, 
the  actual  quantity  of  lime  depending  on  the  amount  of 
carbonate  in  the  water.  The  lime  is  slaked  in  a  tank  into 
which  the  water  to  be  treated  flows;  the  mixture  is  well 
stirred  and  then  allowed  to  stand  for  twelve  hours,  when 


WATER.  153 

the  supernatant  water  is  drawn  off,  the  tank  cleaned  and 
the  process  repeated.  The  water  is  not  only  softened  in 
this  way,  but  the  precipitate  usually  carries  down  with 
it  much  of  the  solid  impurities  and  organic  matters  in  the 
water.  This  process  is  extensively  used  in  England,  where 
much  of  the  available  water  is  derived  from  the  underly- 
ing chalk  beds,  and  thus  has  a  superabundance  of  the 
bicarbonate;  but  the  writer  is  unaware  that  it  finds  any 
general  application  in  this  country,  though  it  might  be  an 
advisable  method  of  treatment  in  certain  of  our  limestone 
districts. 

If  alum  (sulphate  of  alumina)  be  added  to  an  impure 
water,  a  decomposition  of  the  salt  occurs,  the  acid  portion 
combining  with  the  bases  in  the  water  and  forming  a 
flocculent  precipitate  of  insoluble  basic  sulphates  and  alu- 
minum hydrate,  which  entangles  in  it  and  carries  down 
the  suspended  impurities  in  the  water,  besides  remov- 
ing much  of  the  dissolved  organic  and  coloring  matters. 
Moreover,  careful  experiments  have  shown  that  the  addi- 
tion of  only  about  one  grain  of  alum  per  gallon,  followed 
by  thorough  agitation  and  subsequent  settling  for  twenty- 
four  hours,  will  almost  invariably  give  a  water  free  from 
germs  and  one  that  will  tend  to  remain  sterile  for  a  con- 
siderable time;  this  possibly  being  due  to  the  removal  of 
the  food-supply  of  the  bacteria.1 

The  use  of  alum  is  especially  advantageous  when  a 
water  contains  a  very  fine  silt  or  the  like  in  suspension, 
and  which  is  not  removed  by  subsidence  even  after  a  con- 
siderable time.  It  is  also  to  be  used  in  conjunction  with 
or  preliminary  to  mechanical  filtration,  which  latter,  at 
the  usual  rate  of  operation,  is  oftentimes  practically  de- 

i  V.  and  A.  Babes :  Centralblatt  fur  Bakteriologie  und  Parasitenkunde,  1892, 
vol.  xii.,  No.  45. 


154    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

pendent  upon  alum  for  the  furnishing  of  a  safe  water. 
Comparatively  little  alum  is  needed,  usually  not  more 
than  one,  or  at  most  two,  grains  per  gallon,  even  with  a 
very  dirty  water,  and  if  the  supply  is  practically  adjusted 
to  the  condition  of  the  water,  as  it  should  be,  the  extremely 
minute  quantity  of  free  alum  that  may  sometimes  pass 
through  the  filters  is  harmless  and  unimportant. 

Should  the  water  be  lacking  in  sufficient  bases,  which, 
however,  is  extremely  improbable,  it  might  contain  when 
filtered  a  very  little  free  acid,  which  would  be  readily 
neutralized  by  the  addition  of  a  correspondingly  small 
quantity  of  soda,  the  resulting  salt  affecting  neither  the 
healthful  ness  nor  the  palatability  of  the  water.  It  has 
been  suggested  that  the  alum  be  first  decomposed  by  the 
addition  of  soda,  then  washed  free  from  the  resulting 
sodium  sulphate,  and  the  flocculent  hydrate  of  alumina 
added  to  the  water,  thus  avoiding  the  danger  of  either 
free  alum  or  acid  in  the  cleared  water;  but  experiments 
show  that  the  results  are  not  as  good  as  when  alum  alone 
is  used. 

Regarding  the  danger  from  the  use  of  waters  purified 
by  the  addition  of  alum,  Hazen  says  :  "Although  alum 
in  large  quantities  is  undoubtedly  injurious  to  health,  it  is 
neither  a  violent  nor  a  cumulative  poison;  and  the  propo^ 
sition  that  one  part  of  alumina  in  a  million  parts  of  water 
is  injurious  to  health  must  be  regarded  as  conjecture  rather 
than  as  a  matter  of  proof,  or  even  of  probability.'7 

The  Anderson  process,  which  consists  in  the  agitation 
of  the  water  with  metallic  iron  before  filtration,  is  em- 
ployed at  Antwerp  and  elsewhere;  but  it  is  not  clear  that, 
with  large  quantities  of  water,  better  results  are  obtained 
than  by  simple  filtration.  The  idea  is  that  some  of  the 
iron  is  converted  into  soluble  ferrous  carbonate,  which 


WATER.  155 

then  oxidizes  to  insoluble  ferric  hydrate  and  carries  down 
with  it  the  suspended  and  many  dissolved  impurities,  and 
thus  facilitates  their  removal  by  sedimentation  and  filtra- 
tion. The  difficulty  in  using  this  process  on  a  large  scale 
seems  to  be  that  the  carbonate  is  not  formed  quickly 
enough,  and  also  that  too  much  of  the  iron  may  remain 
in  solution  even  after  filtration. 

Filtration.  For  the  purification  of  large  quantities  of 
water,  such  as  are  needed  for  great  cities,  there  can  be  no 
question  that  sand  filtration  is,  in  the  majority  of  cases, 
the  most  available,  satisfactory,  and  efficient  method, 
though  it  may  often  be  advantageously  preceded  by  sedi- 
mentation or  by  chemical  treatment,  as  already  described. 
The  former  especially,  by  removing  much  of  the  sus- 
pended matters,  will  prolong  the  use  of  the  filters  between 
cleanings,  and  thus  materially  lessen  the  cost  of  mainte- 
nance; while  the  latter  may  greatly  improve  the  chemical 
quality  of  the  filtered  water. 

Municipal  filters  of  the  type  to  be  described  are  as  yet 
not  widely  known  in  this  country,  but  they  have  been  used 
abroad  with  increasingly  good  results  for  upward  of  half  a 
century,  and  they  now  furnish  the  daily  supply  of  water 
to  more  than  twenty  millions  of  people.  However,  we 
may  take  credit  in  the  knowledge  that  the  most  thorough 
and  scientific  investigation  of  their  action  and  efficiency 
has  been  made  on  this  side  of  the  Atlantic  under  the 
auspices  of  the  Massachusetts  State  Board  of  Health,  and 
that  it  is  to  this  body  that  we  are  indebted  for  much  of 
the  positive  information  that  we  now  have  concerning 
them. 

The  limitations  of  this  work  do  not  permit  a  full  dis- 
cussion of  the  principles  or  merits  of  such  filters;  but  the 
following  details  are  given  that  the  reader  may  appreciate 


156    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

the  simplicity  of  their  construction  and  the  efficiency  of 
their  work.  Those  desiring  more  extended  information 
are  referred  to  the  Massachusetts  reports  that  discuss  this 
subject,  and  to  the  excellent  work  of  Dr.  Hazen,  already 
mentioned,1  from  which  many  of  the  accompanying  state- 
ments and  the  illustrations  have  been  taken. 

Almost  without  exception  these  filters  now  consist  of  a 
layer  of  clean  sand  of  a  certain  degree  of  fineness  spread 
upon  a  layer  of  gravel  in  a  carefully  prepared  basin,  the 
whole  being  underdrained  and  proper  arrangements  made 
for  the  controlling  of  the  depth  of  water  upon  the  surface, 
rate  of  flow  of  the  filtrate,  cleaning  of  filters,  etc. 

Such  filters  act  primarily  as  strainers  to  remove  the 
solid  impurities  from  the  water,  but  their  efficiency  is 
much  increased  by  the  sediment  itself  that  is  retained 
upon  the  surface  of  the  sand,  and  which  forms  a  filter 
much  finer  than  the  latter  and  is  capable  of  mechanically 
preventing  the  passage  of  most  of  the  bacteria  always 
present  in  a  surface-water.  It  was  supposed  until  com- 
paratively recently  that  this  removal  of  the  bacteria  was 
largely  due  to  the  organisms  themselves  in  the  sediment 
layer,  and  that  by  forming  a  felt-like  growth  they  not 
only  increased  the  fineness  of  the  strainer,  but  that  by 
acting  as  saprophytes  they  decomposed  much  of  the 
organic  matter,  and  even  killed  the  pathogenic  bac- 
teria. However,  it  now  seems  probable  that  for  con- 
tinuous filters  the  action  is  mainly  mechanical,  removing 
suspended  matters  and  bacteria,  and  but  slightly  affecting 
the  dissolved  organic  matters.  On  the  other  hand,  in 
intermittent  filtration,  where  the  conditions  more  nearly 
resemble  those  taking  place  in  the  soil,  and  where  the 

i  Filtration  of  Public  Water  Supplies. 


WATER. 


157 


filters  are  periodically  aerated,  the  straining  action  is  less 
perfect  on  account  of  the  greater  rate  of  nitration  neces- 
sary, but  the  nitrification  and  destruction  of  organic  matter 
due  to  the  action  of  the  saprophytes  and  oxygen  are  greater. 
Intermittent  filters  might,  therefore,  prove  to  be  the  better 
for  the  purification  of  sewage  or  a  very  impure  water, 
though  usually  their  efficiency  in  removing  bacteria  seems 
to  be  inferior  to  that  of  continuous  filters. 

The  location  of  the  filter  beds  with  respect  to  the  source 
of  supply  and  the  storage  reservoirs  will  depend  largely 
on  local  conditions,  economy  in  cost  of  pumping,  etc. 
Settling  tanks  are  almost  essential  where  the  water  to  be 
filtered  is  very  turbid,  even  at  intervals.  Reference  has 


FIG.  25. 


General  arrangement  of  filter  plant. 

already  been  made  to  the  difference  of  opinion  between 
English  and  Continental  authorities  regarding  the  size  of 
these  settling  basins.  As  the  filtration  does  not  remove 
hardness  due  to  dissolved  matters,  it  may  also  be  advisable 
to  use  the  Clark  process  previous  to  sedimentation  and 
filtration.  Part  of  the  color  due  to  peat  or  vegetable 
matters  is  removed  by  ordinary  filtration,  and  still  more 
may  sometimes  be  taken  away  by  the  previous  addition  of 
alum,  but  such  preliminary  treatment  is  unusual.  Where 
the  water  comes  from  a  lake  or  from  a  river  with  a  slow 
current,  settling  basins  are,  of  course,  unnecessary. 


158 


MANUAL  OF  HYGIENE  AND  SANITATION. 


Inasmuch  as  it  is  needful  to  govern  the  depth  of  the 
water  upon  the  filter-beds,  and  to  prevent  the  disturbance 
of  the  sand  and  sediment  layer  by  the  force  of  the  enter- 
ing current,  some  method  of  regulating  the  inflow  is  neces- 
sary. The  accompanying  illustration  shows  a  compara- 
tively simple  arrangement  for  this  purpose. 

FJG.  26. 


0  5  10  15  20  Feet 

Regulation  of  inflow  used  at  Hamburg. 

The  total  area  of  the  filter-beds  will  depend  upon  the 
amount  of  water  needed,  the  rate  of  filtration,  and  the  per- 
centage of  area  out  of  use  while  being  cleaned.  The  total 
area  is  to  be  divided  into  beds  varying  in  number  accord- 
ing to  circumstances,  so  that  one  or  more  of  these  beds 
may  be  cleaned  while  the  rest  are  in  use.  Large  beds 
decrease  the  cost  per  acre,  on  account  of  less  masonry,  etc., 
being  needed,  but  it  may  be  more  difficult  to  maintain  an 
even  action  over  the  larger  areas.  This  latter  point  is, 
however,  largely  governed  by  the  size  and  arrangement 
of  the  underdrains. 

The  walls  and  bottoms  of  filter-beds  should  be  made 
water-tight,  that  there  may  be  no  waste  of  the  filtered 
water  on  the  one  hand,  nor  any  ingress  of  foul  soil-water 


WATER.  159 

on  the  other.  The  form  of  the  filter-bed  is  immaterial, 
provided  evenness  of  work  over  the  whole  area  is  not 
impaired.  Where  the  mean  January  temperature  is  below 
the  freezing  point  the  beds  should  be  covered,  as  the 
formation  of  ice  upon  them  seriously  impairs  their  effi- 
ciency, and  as,  moreover,  a  number  of  epidemics  of  typhoid 
fever  and  certain  intestinal  diseases  seem  to  be  directly 
traceable  to  ice-formation.  This  may  have  been  on  account 
of  the  overtaxing  of  the  filters  through  increased  difficulty 
in  working,  or  because  the  sedimentation  layer  and  the 
sand  were  disturbed  in  the  removal  of  the  ice. 

As  already  stated,  the  materials"  used  practically  every- 
where are  clean  sand  and  gravel,  and  the  sharper  the  sand- 
grains  the  better.  At  the  Lawrence  Experiment  Station 
of  the  Massachusetts  State  Board  of  Health  "  the  size  of 
a  sand-grain  is  uniformly  taken  as  the  diameter  of  a  sphere 
of  equal  volume,  regardless  of  its  shape. "  Moreover,  as 
it  is  "  the  finest  portion  which  mainly  determines  the  char- 
acter of  sand  for  filtration/7  the  effective  size  is  taken  to  be 
<(  the  size  of  a  grain  such  that  10  per  cent,  by  weight  of 
the  particles  are  smaller  and  90  per  cent,  are  larger  than 
itself.77  As  uniformity  of  grain  is  also  important,  the 
uniformity  coefficient  is  "  the  ratio  of  the  size  of  grain 
which  has  60  per  cent,  of  the  sample  finer  than  itself  to 
the  size  which  has  10  per  cent,  finer  than  itself.77  Obvi- 
ously, the  velocity  of  water  through  a  layer  of  sand  will 
depend  upon  the  effective  size  of  the  sand,  the  thickness 
of  the  layer  through  which  the  water  passes,  and  the  loss 
of  head  or  f rictional  resistance  of  the  sand.  A  rise  of 
temperature  also  causes  a  progressive  increase  in  velocity. 

The  effective  sizes  of  sand-grain  in  use  in  most  of  the 
foreign  filters  average  from  0.31  to  0.40  mm.  In  general, 
it  may  be  said  that  the  finer  the  sand,  the  better  is  the 


160    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

quality  of  the  normal  filtrate  and  the  less  the  danger  of 
an  unsafe  effluent  in  case  the  sediment  layer  is  broken; 
but,  on  the  other  hand,  cost  of  filtration  increases  with  the 
smallness  of  sand-grain,  since  the  filters  must  be  cleaned 
oftener  and  fine  sands  are  harder  to  wash,  as  well  as 
because  the  velocity  of  flow  is  slower  through  fine  sands. 
All  things  considered,  the  best  results  will  probably  be 
obtained  with  a  sand  having  an  effective  size  of  from 
0.20  to  0.35  mm.  and  a  uniformity  coefficient  of  not  more 
than  3,  the  lower  the  latter  the  better,  and  the  selection  of 
the  former  depending  largely  upon  the  character  and  clear- 
ness of  the  water  to  be  filtered. 

The  thickness  of  the  sand  layer  should  be  such  that  it 
may  be  scraped  a  number  of  times  before  becoming  so  thin 
as  to  require  refilling.  The  German  Imperial  Board  of 
Health  requires  a  thickness  of  at  least  twelve  inches  after 
the  last  scraping;  while  the  original  thickness  should  be 
from  twenty-four  to  forty-eight  inches,  the  thicker  the 
better,  provided  the  cost  of  the  filter  be  not  made  too 
great  and  the  rate  of  filtration  be  not  too  much  dimin- 
ished. The  sand  should  be  of  the  same  degree  of  fineness 
throughout. 

As  for  the  gravel  beneath  the  sand,  there  is  no  reason 
why  it  should  be  of  excessive  thickness.  A  depth  of  one 
foot  is  probably  sufficient,  provided  the  stones  are  of  vary- 
ing size,  so  arranged  that  the  sand  above  will  not  work 
into  and  through  the  interstices,  and  that  the  water  may 
freely  enter  the  underdrains  at  low  velocity.  The  loss  of 
head  in  water  flowing  through  a  thin  layer  of  gravel  prop- 
erly placed  is  comparatively  slight.  Foreign  filters  do 
have  a  gravel  layer  of  two  feet  or  more  in  thickness,  as  a 
rule,  but  careful  experiments  at  Lawrence,  Mass.,  show 
that  this  depth  is  entirely  unnecessary,  provided  that  the 


WATER.  161 

gravel  is  properly  laid  as  indicated,  and  that  the  under- 
drains  are  not  too  far  apart. 

The  underdrains  should  be  of  such  size  and  so  con- 
structed that  the  frictional  resistance  which  they  offer  to 
the  flow  of  the  water  is  only  a  small  percentage  of  that 
of  the  clean  sand,  and  that  the  rate  of  nitration  is  the  same 
over  the  whole  area  of  the  filter.  There  is  usually  a  main 
drain  along  the  middle  of  the  filter  floor  with  smaller 
parallel  lateral  drains  leading  into  it  at  regular  intervals. 
The  drains  may  be  made  of  brick  with  open  joints,  or,  for 
the  laterals,  of  tile,  which  is  usually  cheaper.  Care  must 
always  be  had  that  the  openings  are  sufficient  in  number 
and  size  freely  to  admit  the  water. 

The  area  drained  should  vary  from  about  300  square 
feet  for  a  four-inch  lateral  drain  to  4400  square  feet  for  a 
twelve-inch  main,  the  velocity  of  flow  in  these  being 
respectively  0.30  and  0.51  foot  per  second;  while  larger 
drains  should  have  a  cross-section  of  at  least  one-six-thou- 
sandths of  the  drained  area.  The  European  custom  of 
ventilating  drains  by  means  of  pipes  passing  up  through 
the  sand  and  water  above  is  not  to  be  commended,  since 
such  ventilation  apparatus  is  unnecessary,  increases  the 
cost  of  the  filters  and,  what  is  worse,  may  allow  impurities 
to  contaminate  the  filtered  water  in  the  drain.  Recently 
it  has  been  suggested  that  the  filter-beds  be  constructed 
directly  over  the  storage  reservoirs  for  the  filtered  water, 
the  beds  being  supported  on  suitable  steel  columns  resting 
on  concrete  foundations  in  the  bottom  of  the  reservoirs. 
The  bottom  layer  of  gravel  or  broken  stone  would  rest  on 
steel  tubes  or  bars  several  feet  above  the  level  of  the 
water  in  the  reservoir,  thus  allowing  the  filtrate  to  be 
aerated  as  it  falls  through  the  intervening  space.  Theo- 
retically it  would  seem  that  the  plan  is  a  good  one,  and 

11 


162    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

actual  results  indicate  that  it  practically  is  so.  Some  of 
the  advantages  are  the  absence  of  underd rains  and  loss  of 
the  resistance  factor  due  to  them,  the  aeration  of  the 
nitrate  as  indicated,  and  also  the  practically  continuous 
aeration  of  the  filter-bed  itself,  thus  enabling  the  sapro- 
phytic  bacteria  in  the  upper  layers  to  carry  on  their  work 
of  oxidizing  and  nitrifying  the  organic  impurities  of  the 
water. 

The  depth  of  water  upon  the  filter-beds  must  be  regu- 
lated according  to  the  rate  of  flow  desired,  the  thickness 
and  resistance  of  the  sand,  etc.  Although  it  has  been  the 

FIG.  .27. 


Simplest  form  of  regulation.    Stralau  filters  at  Berlin. 

custom  to  keep  the  depth  in  excess  of  the  loss  of  head, 
this  is  not  essential.  On  foreign  filters  the  usual  depth  is 
from  thirty-six  to  fifty-two  inches,  though  less  than  this 
might  suffice  in  many  instances.  The  necessity  of  regu- 
lating the  inflow  and  of  maintaining  a  constant  level  must 
not  be  overlooked  if  uniform  results  are  desired. 

Summarizing  the  preceding  statements,  the  rate  of  filtra- 
tion and  loss  of  head  will  depend  upon  the  depth  of  water 


WATER.  163 

on  the  filters,  the  thickness  of  the  sand-layer,  size  of  sand- 
grains,  resistance  of  underdrains,  temperature,  etc.,  and 
all  these  will  likewise  affect  both  the  cost  and  the  efficiency 
of  the  filtration. 

Two  million  gallons  per  acre  per  day  will  probably  be  a 
safe  rate  of  filtration  to  maintain  continuously,  though  with 
a  clear  water  or  in  emergencies  a  rate  one-half  greater  will 
very  likely  not  materially  alter  the  quality  of  the  filtered 
water  or  increase  the  risk.  But  in  general,  as  the  rate 
increases  the  efficiency  decreases.  Where  the  filters  are 
constructed  above  the  storage  reservoirs  in  the  manner 
described,  it  is  claimed  that  much  larger  quantities  of 
water  may  be  filtered  in  the  given  time  with  equally  good 
results.  If  this  be  so,  it  is  probably  due  to  the  increased 
saprophytic  and  oxidizing  action  resulting  from  the  con- 
tinuous aeration  of  the  filter. 

As  the  sediment  accumulates  and  deepens  upon  the  sur- 
face of  the  sand,  the  rate  of  flow  necessarily  diminishes, 
and  it  becomes  necessary  after  a  time  to  remove  the  de- 
posit. This  is  done  by  carefully  scraping  off  the  top 
layer  of  the  sand  to  the  depth  of  from  one-half  to  one 
and  one-half  inches,  repeating  the  scraping  as  often  as 
may  be  necessary  until  the  thickness  of  sand  above  the 
underlying  gravel  is  near  the  permissible  minimum. 
Then  the  sand  which  has  been  removed,  and  which  has 
meanwhile  been  thoroughly  washed  by  a  stream  of  the 
filtered  water,  driven,  if  necessary,  by  a  force-pump  is  care- 
fully replaced,  packed,  and  levelled  upon  the  beds.  How- 
ever, these  do  not  attain  their  greatest  efficiency  until  a  cer- 
tain amount  of  sediment  from  the  water  has  collected  upon 
them,  and  it  is,  therefore,  not  wise  to  use  the  filtered  water 
for  some  time  after  the  cleaning  and  until  bacteriological 
tests  show  that  the  maximum  purification  is  being  attained. 


164    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

Domestic  Purification  of  "Water.  Boiling  destroys 
living  organisms  and  disease  germs;  it  also  drives  off  the 
carbonic  acid  and  other  gases  of  the  water,  and  causes  the 
precipitation  of  many  mineral  substances  held  in  solution  by 
these  gases.  This  is  especially  the  case,  as  has  been  stated, 
where  the  water  is  hard  from  the  presence  of  calcium 
bicarbonate  in  excess,  but  iron  is  also  often  thrown  down 
by  boiling.  If  the  water  contains  a  very  fine  sediment,  not 
removed  by  settling  or  filtration,  it  may  be  advantageous 
to  add  a  little  alum  and  chalk  to  produce  the  flocculent 
precipitate  already  described.  Potassium  permanganate 
has  little  effect  in  purifying  a  foul  water.  Agitation  with 
iron  filings  may  do  a  little  good  by  favoring  oxidation  of 
organic  matters.  Tannin  is  thought  to  destroy  micro- 
organisms, and  a  harmful  water  may  sometimes  be  made 
usable  •  by  boiling  with  tea  leaves  or  other  astringents. 
Citric  acid  is  said  to  destroy  algae.  Aeration  and  agitation 
improve  a  water  after  distillation  or  boiling  by  restoring 
oxygen  and  also  by  oxidizing  organic  matters.  Eemem- 
ber  that  boiled  water  is  prone  to  take  up  gases  of  any 
kind,  whether  impure  and  offensive  or  otherwise.  Organic 
matters  are  got  rid  of  by  boiling,  exposure  to  air,  agita- 
tion, addition  of  alum,  astringents,  charcoal,  etc. ;  bicar- 
bonate of  lime,  by  boiling  or  by  adding  caustic  or  slaked 
lime;  iron,  by  boiling  and  by  adding  lime-water.  Cal- 
cium and  magnesium  sulphate  and  chloride  cannot  readily 
be  removed.  Some  plants  help  to  purify  by  means  of  the 
oxygen  which  they  give  to  the  water. 

House  filters  are  dangerous  unless  properly  cared  for, 
and  may  give  more  and  worse  impurities  to  the  water 
than  they  take  from  it.  What  a  filter  takes  from  a  water 
is  left  in  the  filter,  unless  otherwise  removed,  and  an  accu- 
mulation of  such  impurities  cannot  improve  the  water 


WATER. 


165 


passing  through  them.  The  organic  matters  will  undergo 
decomposition  and  putrefaction,  and  will  furnish  a  good 
culture  medium  for  bacteria,  and  these  together  with  the 
putrefaction  products  will,  in  most  cases,  be  carried  through 
the  filter  with  and  by  the  filtered  water.  A  filter  has  no 
miraculous  power  to  annihilate  filth,  and,  moreover,  the 
size  of  a  filter  must  always  limit  the  work  it  can  do,  what- 
ever the  materials  used. 

According  to  Parkes,  the  requisites  of  a  good  filter  are : 
1.  That  every  part  shall  be  easily  accessible  for  cleansing 
or  renewing  the  medium.  2.  That  the  filtering  medium 
have  a  sufficient  purifying  power  and  be  present  in  suffi- 
cient quantity.  3.  That  the  medium  give  nothing  to  the 
water  favoring  the  growth  of  low  forms  of  life.  4.  That 
the  purifying  power  be  reasonably  lasting.  5.  That  there 
be  nothing  in  the  construction  of  the  filter  itself  capable 
of  undergoing  putrefaction  or  of  yielding  metallic  or  other 
impurities  to  the  water.  6.  That  the  filtering  material 

FIG.  28. 


Tubes  of  unglazed  porcelain  for  Pasteur  filter. 

shall  not  clog,  and  that  the  flow  of  water  be  reasonably 
rapid;  to  which  may  be  added  :  7.  That  the  filtering  me- 
dium be  such  that  it  can  be  readily  cleansed  and  sterilized, 
or  else  so  cheap  that  the  removal  and  replenishing  may 
not  be  neglected  when  necessary  on  account  of  the  expense. 
House  filters  may  be  divided  into  three  classes :  (a) 
Those  entirely  disconnected  from  the  water-supply  pipes 
of  the  house;  (6)  those  connected  with  the  water-pipes, 


166    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

but  intended  to  filter  only  a  limited  quantity,  as  for 
drinking,  cooking,  etc.;  (c)  those  connected  with  the 
house  service-pipe  and  intended  to  filter  all  the  water  used 
in  the  house.  The  same  filtering  media  may  be  used  in 
all  three  classes,  but  it  will  be  found  best  in  the  first  two 
to  employ  substances  through  which  the  water  passes 
slowly,  while  the  latter  class  must  necessarily  filter  the 
water  more  rapidly  in  order  to  yield  a  sufficient  supply. 

FIG.  29. 


Berkfeldt  filter  attached  to  tap. 

It  will  often  be  advantageous  to  have  a  settling  tank  con- 
connected  with  those  of  the  first  class,  to  prolong  the  safe 
use  of  the  filter  as  long  as  possible;  while  the  same  object 
is  gained  in  some  of  the  second  class  by  bringing  the  water 
in  at  the  bottom,  in  which  case  there  should  be  a  space 
below  the  filtering  medium  to  allow  the  suspended  matters 
to  fall  away  from  the  latter.  Those  intended  to  filter  the 
whole  supply  of  the  house  are  generally  cleansed  by 
reversing  the  current  and  washing  the  collected  dirt  out 
of  the  filter  into  a  drain  or  sewer,  the  first  water  passing 


WATER. 


167 


through  the  filter  after  this  is  done  being  also  discarded. 
In  such  filters  the  quantity  of  filtering  material  should  be 
sufficient  thoroughly  to  purify  the  water  passing  through 


FIG.  30. 


Pasteur  filter  with  reservqir  for  filtered  water. 

it,  and  yet  should  not  be  so  heavy  that  the  reverse  or 
washing  current  'cannot  lift  it  and  separate  the  particles 
so  that  by  their  scouring  action  upon  one  another  they 
may  be  cleansed  and  all  the  dirt  washed  out.  These 


168 


MANUAL  OF  HYGIENE  AND  SANITATION. 


filters,  also,  may  be  so  arranged  that  a  small  quantity  of  a 
coagulant,  like  alum,  is  automatically  added  to  the  water 
before  filtration.  If  this  be  done,  care  must  be  had  to 
supply  no  more  of  the  coagulant  than  suitable  tests  show 
to  be  necessary,  else  the  excess  may  be  carried  through  the 
filter  in  solution. 

FIG.  31. 


Multiple  Berkfeldt  filter  with  self-cleansing  attachment. 

No  matter  what  kiud  of  filter  is  used,  the  drinking- 
water  should  always  be  boiled  in  times  of  epidemics,  or 
when  the  water  before  filtration  is  especially  impure;  for, 
though  the  Berkfeldt  or  the  Pasteur-Chamberland  filter, 
and  possibly  a  few  others,  are  practically  bacteria  proof, 


WATER.  169 

there  always  remains  a  possibility  that  disease  germs  may 
by  some  means  pass  through  the  medium  or  gain  access  to 
the  water  after  it  is  filtered.  The  writer's  own  opinion  is 
that  with  most  good  filters  that  are  regularly  and  frequently 
cleaned  there  is  an  action  very  similar  to  that  which  takes 
place  in  filter-beds  on  a  large  scale,  and  that  ordinarily  few, 
if  any,  bacteria  pass  through  with  the  water;  but,  never- 
theless, the  risk  should  not  be  taken,  if,  at  any  time,  there 
is  danger  of  incurring  disease. 

Filters  in  which  the  material  is  cemented  up  so  that  it 
cannot  be  removed  for  cleaning  or  renewal  should  not  be 
used.  Sponge,  wool,  etc.,  are  liable  to  decompose  and 
give  organic  matter  to  the  water,  and  cannot  be  thoroughly 
cleaned.  Asbestos  acts  only  as  a  mechanical  filter,  and 
may  allow  albuminous  matter  and  disease  germs  to  pass. 
Asbestos-cloth  may  be  used,  however,  to  support  the  other 
filtering  media  in  those  filters  where  the  water-supply 
enters  at  the  bottom,  and  it  has  the  advantage  that  it  can  be 
perfectly  sterilized  by  fire.  Small  tap  filters  are  insuffi- 
cient for  the  work  required  of  them,  and  soon  clog.  Pocket 
filters  are  simply  strainers  and  have  little  oxidizing  power. 
They  may  be  quite  useful  for  tourists,  hunters,  etc.,  but 
should  be  frequently  sterilized  by  boiling.  Ordinarily, 
filters  should  not  be  placed  in  rain-water  cisterns,  but 
outside  where  they  may  be  easily  cleaned. 

The  best  filtering  media  are  sand,  animal  charcoal,  mag- 
netic carbide  of  iron,  spongy  iron,  etc.  Unglazed  porcelain 
or  bisque,  as  is  used  in  the  Pasteur-Chamberland  filter,  is 
an  excellent  medium,  and  is  practically  germ  proof,  though 
some  observers  state  that  bacteria  will  pass  through  un- 
cleaned  filters  of  this  material  after  five  or  six  days. 
Others  claim  that  these  are  not  bacteria,  but  only  the 
mycelia  of  certain  budding  fungi  with  no  power  of  repro- 


170 


MANUAL  OF  HYGIENE  AND  SANITATION. 


duction.  Stone  filters  may  be  good  and  resemble  the  por- 
celain ones  in  action,  but  are  apt  to  be  slow,  and  must  be 
cleansed  often. 

FIG.  32. 


Glass  model  of  Loomis-Manning  filter,  showing  filter  in  action. 

Sharp,  clean  sand,  not  too  fine,  has  fair  filtering  proper- 
ties, as  it  stops  most  of  the  suspended  matters  and  bacteria, 


WATER. 


171 


beside  oxidizing  somewhat  the  dissolved  organic  matters. 
It  makes  a  good  first  layer  for  a  filter,  because  it  is  cheap 


FIG.  33. 


Glass  model  of  Loomis-Manning  filter,  showing  material  during  cleansing. 

and  can  be  easily  renewed  or  cleaned  and  sterilized  by 
boiling.    Crushed  quartz  is  of  practically  the  same  nature. 


172    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

Animal  charcoal  is,  when  fresh,  an  excellent  material, 
as  it  removes  both  suspended  and  dissolved  matters, 
organic  and  inorganic,  and  even  color.  It  acts  both  me- 
chanically and  chemically,  and  with  a  good  volume  of  it 
water  may  pass  through  rapidly  and  be  well  purified. 
But  after  a  time  it  ceases  to  be  effective,  and  water  must 
not  be  left  in  contact  with  it  long,  as  it  will  give  up 
organic  matter  to  the  water  again,  and  also  phosphate  of 
lime,  the  latter  especially  favoring  the  development  of 
micro-organisms.  Moreover,  fresh  organic  matters,  and 
possibly  bacteria  are  said  to  pass  through  it  readily,  though 
dead  or  decomposing  matter  is  rapidly  destroyed.  It 
should  be  changed  or  cleansed,  even  when  in  sufficient 
bulk,  three  or  four  times  a  year;  oftener  if  the  water  to 
be  filtered  is  very  bad.  It  is  more  efficacious  than  any 
other  substance  in  removing  lead  from  water. 

Magnetic  carbide  of  iron  is  one  of  the  best  filtering 
materials,  as  it  has  considerable  power  in  oxidizing  organic 
matters,  converting  them  into  nitrates  and  nitrites,  the 
action  being  greater  the  longer  the  water  is  in  contact  with 
it.  It  acts  partly  by  surface  condensation  of  oxygen; 
partly,  perhaps,  by  electrolytic  action.  If  sand  be  used 
as  a  first  layer  to  remove  solid  matters,  so  that  the  water 
reaches  the  carbide  perfectly  clear,  and  if  the  sand  be  fre- 
quently renewed  or  cleansed,  the  carbide  need  never  be 
changed;  but  the  filtration  must  be  intermittent,  so  that 
the  carbide  may  be  frequently  aerated.  Spongy  iron  has 
an  action  very  similar  to  that  of  the  magnetic  carbide  on 
organic  matter,  and,  like  it,  the  action  is  the  greater  the 
longer  the  contact.  It  must  be  kept  covered  with  water 
to  prevent  rusting  and  caking,  and  should  be  renewed 
about  once  a  year.  The  small  amount  of  iron  that  the 
magnetic  carbide  and  spongy  iron  give  to  the  water  may  be 


WATER.  173 

removed  by  passing  it  through  a  layer  of  pyrolusite,  a  crude 
oxide  of  manganese.  A  mixture  of  pyrolusite  and  sand, 
or  crushed  quartz,  makes  an  excellent  filtering  material. 

Ice  should  not  be  added  to  filtered  or  drinking-water, 
as  freezing,  even  for  a  long  time,  may  not  kill  certain 
disease  germs.  Prudden  has  kept  typhoid  bacilli  frozen 
in  ice  for  over  three  months  without  destroying  their 
power  of  growth  and  reproduction  when  brought  to  a 
suitable  temperature.  The  same  objections  do  not,  of 
course,  pertain  to  artificial  ice  carefully  made  from  dis- 
tilled-water  as  to  that  from  polluted  ponds  or  rivers;  but 
it  is  well  to  cool  the  water  by  placing  it  in  stoppered  bottles 
upon  ice  or  in  vessels  surrounded  by  ice,  rather  than  by 
adding  ice  to  the  water  directly. 

The  examination  of  a  drinking-water  should  have  regard 
to  its  physical,  bacteriological,  and  chemical  properties,  as 
well  as  to  a  consideration  of  all  the  circumstances  affecting 
its  source,  storage,  and  distribution.  Consequently,  a 
decision  on  the  purity  of  a  water  should  be  governed  by 
all  the  circumstances  available:  whether  it  is  well-, 
spring-,  rain-,  or  river-water;  whether  it  has  been  at  any 
time  exposed  to  pollution;  in  what  kind  of  a  cistern  or 
reservoir  it  has  been  stored,  etc. 

A  physical  examination  of  water  considers  the  color, 
clearness,  sediment,  lustre,  taste,  and  smell.  Pure  water 
has  a  bluish  tint,  but  most  waters  are  grayish,  greenish, 
yellow,  or  brown.  Yellow  or  brown  waters  are  suspi- 
cious, as  the  color  may  be  due  to  animal  matter  or  sewage, 
though  vegetable  matters  or  iron  may  give  the  same  color. 
Green  waters  are  usually  harmless,  the  color  being  due  to 
vegetable  matters.  The  color  is  judged  by  allowing  the 
sediment  to  settle  and  pouring  off  the  supernatant  water 
into  a  tall  glass  vessel  or  tube  to  the  depth  of  about 


174    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

twenty-four  inches;  the  color  is  then  compared  with  a 
similar  depth  of  distilled  water,  looking  down  through 
both  upon  a  white  surface,  or,  after  sealing  the  tops  of  the 
tubes  with  glass  plates,  by  looking  through  each  in  turn 
at  a  white  light. 

The  clearness  of  a  water  is  to  be  estimated  in  the  same 
way  as  above,  except  that  the  sediment  is  to  be  shaken  up 
with  the  water.  The  depth  needed  to  obscure  print  may  be 
used  as  an  index.  Where  the  solid  matter  will  not  settle, 
owing  to  the  minuteness  and  lightness  of  the  particles,  one 
should  determine  whether  the  use  of  a  coagulant  and  filtra- 
tion is  indicated,  or  whether  boiling  will  tend  to  precipitate 
the  sediment.  The  sediment  may  be  roughly  judged  by  the 
eye  as  to  whether  it  is  mineral  or  otherwise;  it  should  also 
be  examined  microscopically,  for  which  purpose  it  may  be 
collected  by  using  a  centrifugal  apparatus  or  by  allowing 
it  to  settle  from  the  water  in  a  conical  glass,  and  then 
removing  it  to  the  slide  with  a  pipette.  Mineral  matters 
are  recognized  by  their  crystalline  or  amorphous  struc- 
ture or  by  micro-chemical  tests;  vegetable  cells,  portions 
of  leaves,  etc.,  by  their  structure  and  the  presence  of 
chlorophyll;  animal  substances,  as  hair,  wool,  epithe- 
lial and  other  cells,  by  their  peculiar  characteristics. 
Dark  brown,  globular  masses  may  come  from  sewage. 
Anything  indicating  that  water  has  come  from  human 
habitation  renders  it  suspicious,  as  it  may  contain  sewage  or 
other  polluting  substances.  Some  of  the  larger  animalculae 
and  sometimes  iron  may  be  detected  with  the  naked  eye.1 

The  lustre  is  supposed  to  indicate  the  amount  of  aera- 
tion; it  may  be  nil,  dull,  vitreous,  or  adamantine.  It 
should  not  be  forgotten  that  a  very  impure  water  may  be 
clear,  bright,  and  sparkling. 

1  See  J.  C.  MacDonald's  Guide  to  Microscopic  Examination  of  Drinking-water. 


WATER.  175 

Any  badly  tasting  water  should  be  considered  suspicious. 
Dissolved  animal  matters  may  be  tasteless,  but  suspended 
substances  give  a  peculiar  taste,  whether  animal  or  vegeta- 
ble. Iron  is  about  the  only  ordinary  mineral  that  can  be 
tasted  in  small  quantities.  Good  water  depends  for  its  taste 
mainly  upon  its  gases,  and  water  free  from  gas  tastes  flat. 

The  smell  of  a  water,  if  it  has  any,  may  be  brought  out 
by  heating  gently  to  about  110°  F.,  or  by  boiling  it. 
This  may  make  evident  a  fecal  odor,  although  sulphu- 
retted hydrogen  may  mask  this  latter;  in  such  a  case  the 
sulphuretted  hydrogen  may  be  removed  by  adding  a  little 
copper  sulphate  to  the  water.  The  odor  may  also  be  devel- 
oped by  allowing  the  water  to  stand  in  a  corked  bottle  in 
a  warm  place  for  a  few  days. 

A  bacteriological  analysis  is  almost  as  necessary  as  a 
chemical  one,  for  purity  in  the  one  respect  does  not  neces- 
sarily indicate  purity  in  the  other.  The  presence  of  the 
bacterium  coli  communis  in  a  water,  irrespective  of  any 
pathogenic  organisms,  would  create  a  suspicion  of  con- 
tamination by  fecal  matter,  as  this  microbe  is  practically 
a  constant  occupant  of  the  human  intestinal  tract. 

Water  may  be  collected  for  bacteriological  analysis  in 
sterilized,  closed  bulbs  blown  from  glass  tubing.  The 
heat  used  in  sealing  the  ends  creates  a  partial  vacuum 
within  the  bulb,  so  that  if  the  tip  of  one  end  be  broken 
off  beneath  the  surface  of  the  water,  the  latter  is  drawn 
up  into  the  bulb,  which  can  then  be  resealed  and  conveyed 
to  the  laboratory.  But  it  is  always  best,  if  possible,  to 
inoculate  the  culture-media  at  the  place  where  the  supply 
for  examination  is  obtained,  as  the  bacteria  multiply  rap- 
idly in  transportation,  and  some  species  may  even  destroy 
others.  This  can  be  done  by  adding  a  small  quantity  of 
water  to  melted  nutrient  gelatine  and  making  plate  cultures 


176    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

in  the  manner  already  described.  The  number  of  colonies 
resulting  therefrom  will  indicate  practically  the  number 
of  bacteria  in  the  quantity  of  water  added  to  the  gelatine. 

The  details  of  the  tests  and  methods  employed  in  the 
chemical  analysis  of  drinking-water  will  be  given .  in 
another  chapter.  Here  we  need  only  consider  the  influ- 
ence that  the  substances  sought  for  in  the  analysis  have  in 
affecting  potability  and  within  what  limits  we  may  con- 
sider them  as  being  permissible  in  drinking-water.  The 
water  should  be  filtered  or  free  from  sediment  for  all  the 
tests,  except  in  the  estimation  of  nitrogen  as  ammonia 
compounds  and  as  organic  matter,  and  of  the  oxygen- 
consuming  power  of  the  water. 

The  amount  of  total  solids  will  vary  with  the  source  of 
the  water,  and  much  more  might  be  present  in  some  cases 
than  would  be  safe  in  others;  but  usually  the  proportion 
should  not  exceed  50  or  60  parts  in  100,000.  Only  a 
small  portion  should  be  volatile,  and  there  should  be  little 
charring  or  ignition,  except  in  the  case  of  waters  from 
peaty  soils;  nor  should  there  be  any  odor  on  ignition,  espe- 
cially of  ammonia  compounds,  as  that  would  indicate  an 
excess  of  animal  organic  matter.  Deep  well-water  will 
probably  have  much  more  total  solids  than  rain-  or  river- 
water,  the  excess  being  mainly  mineral  substances  dis- 
solved from  the  strata  through  which  the  water  passes. 

Even  the  purest  waters  contain  a  little  chlorine,  usually 
in  the  form  of  sodium  chloride;  but  as  the  latter  is  a  con- 
stant constituent  of  household  slops  and  sewage  in  gen- 
eral, any  excess  of  chlorine  above  the  amount  common  to 
the  water  of  the  district,  unless  otherwise  accounted  for, 
will  be  decidedly  suspicious,  and  sewage  contamination 
should  be  looked  for.  So,  also,  any  sudden  increase  in 
the  proportion  of  chlorine  would  very  likely  indicate  the 


WATER.  177 

accession  of  some  new  supply  of  contamination  to  the  water. 
Unless  accounted  for  by  the  strata  traversed,  more  than  three 
parts  of  chlorine  in  100,000  of  water  is  very  suspicious. 

The  presence  of  considerable  "free  ammonia "  in  rain- 
water is  not  a  bad  sign,  as  it  has  probably  been  absorbed 
from  the  air;  but  the  same  amount  in  subsoil- water, 
especially  if  with  an  excess  of  chlorine,  would  indicate 
probable  contamination  with  urine,  as  this  latter  rapidly 
undergoes  ammoniacal  putrefaction.  In  such  a  case  there 
will  probably  also  be  considerable  "  albuminoid  ammo- 
nia/7 but  much  albuminoid  ammonia  with  little  free 
ammonia  and  chlorine  generally  indicates  vegetable  con- 
tamination. The  writer  is  acquainted  with  a  case  in 
which  the  albuminoid  ammonia  and  chlorine  are  in  marked 
excess,  the  former  being  altogether  of  vegetable  origin — 
from  a  peaty  soil — and  the  latter  characteristic  of  the 
whole  district.  The  free  ammonia  is,  however,  slight  in 
amount.  An  excess  of  free  ammonia,  chlorine,  nitrates  and 
nitrites  indicate  animal  contamination,  though,  if  the  pol- 
lution be  by  effluvia  alone,  there  may  be  no  excess  of 
chlorine.1  The  total  ammonia  in  a  usable  water  should 
not  be  over  0.13  or  0.15  parts  per  1,000,000.  If  there 
is  almost  no  "free"  ammonia,  the  "albuminoid"  may 
amount  to  0,10  parts  per  1,000,000  without  giving  cause 
for  suspicion;  likewise,  if  there  is  but  little  "albumi- 
noid," there  may  be  considerable  "free"  ammonia;  but 
if  the  "  albuminoid"  exceeds  0.5  parts  per  1,000,000,  the 
"free"  must  not  be  greater  than  this  proportion.  The 
simplest  test  for  ammonia  is  by  means  of  Nessler's  reagent, 
a  solution  of  a  double  iodide  of  potassium  and  mercury. 
It  gives  a  yellow  or  yellowish-brown  coloration  when  am- 
monia is  present. 


1  Kenwood's  Hygienic  Laboratory,  p.  49. 
12 


178-4  MANUAL  OF  HYGIENE  AND  SANITATION. 

Organic  matters  of  animal  origin,  and,  therefore,  nitro- 
genous, are,  during  oxidation,  converted  partially  into 
ammonium  compounds,  and  these,  by  the  action  of  certain 
bacteria,  may  be  further  oxidized  into  nitrites  and  nitrates. 
"  Nitrification  takes  place  under  the  influence  of  microbes, 
the  habitat  of  which  does  not  extend  more  than  a  few 
yards  below  the  surface  of  the  soil.  The  nitrifying  action 
is  probably  exerted  only  upon  the  ammonium  which  is 
formed  from  the  organic  matter.  The  presence  of  some 
substance  capable  of  neutralizing  acids  is  necessary  to  con- 
tinuous action.  Calcium  and  magnesium  carbonates  fulfil 
this  function.  Nitrates  are  the  final  result  of  this  action ; 
nitrites  are  present  at  any  given  time,  only  in  small  quan- 
tity. "l  Deep  water  may,  of  course,  also  contain  nitrates 
taken  up  from  strata  rich  in  these  salts. 

Although  nitrites  and  nitrates  are  not  at  all  harmful 
in  the  quantities  usually  found  in  water,  and  though  the 
water  containing  them  may  have  been  thoroughly  purified 
by  long  filtration,  their  presence,  as  will  be  seen  from  the 
above  remarks,  is  important  in  determining  the  character 
of  the  water.  The  presence  of  the  slightest  trace  of  nitrites 
is  always  suspicious,  and  any  marked  amount  of  nitrates, 
excepting  possibly  in  a  deep  water,  should  require  close 
investigation;  the  nitrates  and  nitrites  together  measured 
in  terms  of  nitrogen  should  not  exceed  one  part  per  million. 

The  hardness  should  not  be  greater  than  that  indicated 
by  20  or  30  parts  of  chalk  in  100,000,  and  the  more 
u  temporary"  in  proportion  to  the  "  permanent"  hard- 
ness the  better. 

Phosphates,  not  from  phosphatic  strata,  help  to  indicate 
sewage  contamination.  So,  also,  do  sulphates,  though 
these  by  themselves  may  come  from  harmless  sources. 

1  Leffmann  and  Bevam  :  "  Examination  of  Water,"  2d  edition,  p.  13. 


WATER. 


179 


It  will  be  seen  from  the  above  that  the  opinion  regard- 
ing any  water  must  be  based  on  a  broad  consideration  of 
all  the  circumstances  in  connection  with  it,  and  not  from 
the  presence  or  absence  in  it  of  any  one  or  two  substances, 
which  are  not  in  themselves  harmful.  The  presence  of 
poisonous  metals  above  the  limits  of  safety  would,  however, 
alone  contraindicate  the  use  of  a  water.  For  instance,  there 
should  not  be  more  than  one-twentieth  of  a  grain  of  lead 
or  copper,  one-fourth  grain  of  zinc,  or  one-half  grain  of  iron 
in  any  water,  and  the  faintest  trace  of  arsenic  condemns  it. 

The  following  table  has  been  adapted  from  Parkes  : 

PROPERTIES. 


Class. 

Physical. 

Microscopical. 

Chemical 
(Parts  per  100,000). 

I. 

Colorless  or  bluish 

Mineral   matter  ; 

Chlorine  under       1.4 

Pure 

tint  ;   transparent,    i  vegetable   eiido- 

Total  solids  under  7.14 

water. 

sparkling,  and  well  l  chrome;  large  ani-    Ammonia  under     0.007 

aerated;  no  sediment    mal  forms  ;   no  or-  |  Nitrogen,  as  nitrites 

visible  ;   no   smell  ;    ganic  debris.              \  &  nitrates,  under    0.023 
taste  palatable.                                                Total  hardness       8.5 

II. 

Colorless  or  slight 

Same  as  for  pure    Chlorine  under      4.3 

Usable 

greenish  tint;  trans-    water.                          Total  solids  "       42.8 

water. 

parent,  sparkling, 

Ammonia  under     0.015 

and  well  aerated;  no 

Nitrogen,  as  nitrites 

suspended    matter, 

&  nitrates  under  0.125 

or  easily  separated 

Total  hardness      17.3 

by  coarse  filtration 

or  subsidence  ;   no 

smell  ;  taste  palata- 

ble. 

III. 

Suspicious 

Yellow  or    strong      Vegetable  and  ani- 
green  color  ;  turbid  ;    mal  forms,  more  or 

Chlorine         4  to  7 
Total  solids  43  to  71 

water.       considerable  sus-        less  pale  'or  color-    Ammonia  0.015  to  0.023 

peuded  matter  ;  no    less  ;  organic  debris;     Nitrogen,  as  nitrites 
smell  ;   but  any         fibres  of  clothing  or      and  nitrates 

marked  taste.              other  house  refuse.    !                    0.125  to  2.47 

Total  hardness, 

above                   17 

IV. 

Yellow  or  brown 

Bacteria  of  anv        Chlorine  above       7.14 

Dangerous    color;   turbid,   and  '  kiud;  fungi;  numer-    Total  solids    "       71.4 

water.     ;  not   easily   purified 

ous  vegetable  or  ani-     Ammonia  above     0.0225 

i  by  coarse  filtration  ;    mal   forms  of  low  I  Nitrogen,  as  nitrites 

large  amount  of  sus-    types  ;   epithelia  or 
pended  matter  ;  any    other  animal  struc- 

&  nitrates,  above  0.026 
Total  hardness, 

marked   smell   or 

tures  ;   evidence   of 

above                   28.5 

taste. 

sewage  or    ova    of 

parasites,  etc. 

CHAPTER    VI. 

FOOD. 

THE  use  of  food  is  necessary  to  build  up  the  body 
structure,  to  repair  waste,  and  to  furnish  force  and  energy 
for  the  proper  action  of  all  the  organs,  tissues,  and  parts  of 
the  body.  In  addition,  certain  substances  are  needed,  not 
so  much  because  they  become  a  part  of  the  tissue  frame- 
work or  yield  kinetic  energy  directly,  as  that  they  are 
essential  factors  in  the  multitudinous  chemical  reactions 
and  changes  that  are  continually  occurring  within  the 
living  person.  We  may,  accordingly,  define  a  food  as 
anything  that  tends  to  fulfil  any  one  of  these  functions, 
provided  it  is  not  at  the  same  time  by  nature  harmful  to 
the  economy  and  that  it  does  not  produce  physiological 
effects  out  of  all  proportion  to  its  nutritive  or  metabolic 
activities. 

Strictly  speaking,  this  definition  might  include  air  and 
water,  as  the  former  is  necessary  to  supply  oxygen  for 
union  with  other  foods  or  with  the  tissues  themselves,  in 
order  to  produce  the  heat  and  vital  energy  of  the  body, 
and  the  latter  is  needed  to  assist  in  the  solution  and  assimi- 
lation of  food-stuffs,  to  maintain  the  fluidity  of  the  body 
juices  and  keep  the  tissues  effectively  moistened,  to  pre- 
serve roundness  of  form,  and  to  flush  out  and  remove  from 
all  parts  of  the  system  those  waste  matters  and  excremen- 
titious  substances  whose  retention  gives  rise  to  the  symp- 
toms of  certain  autogenetic  diseases.  But  they  are  not 
usually  included  in  the  category  of  foods,  and,  as  we  have 


FOOD.  181 

already  considered  them  at  length,  they  may  be  passed 
over  in  this  connection  with  but  incidental  reference  here 
and  there. 

If  we  classify  foods  according  to  their  chemical  com- 
position, we  may  separate  them  into  the  followng  main 
divisions  : 

1.  Proteids  and  albuminoids.  2.  Carbohydrates.  3. 
Hydrocarbons  or  fats,  and  4.  Salts,  extractives,  etc.  Each 
group  is  subject  to  different  digestive  and  metabolic  pro- 
cesses, and  each  has  usually  a  different  office  within  the 
body;  for  experience  and  careful  experiments  both  show 
that  all  forms  of  these  different  classes  of  food  are  needed 
to  sustain  life  and  maintain  health  for  any  considerable 
length  of  time,  and  that  with  them  nothing  else  is  abso- 
lutely necessary;  although  what  are  sometimes  called  the 
accessory  food-stuffs  and  many  pleasant  volatile  odors  and 
flavors  are  desirable  and  advisable  adjuncts  to  the  food 
proper,  since  they  greatly  favor  its  reception,  digestion, 
and  assimilation.  But,  though  each  class  of  food  has  its 
own  special  function  in  the  economy  of  nutrition,  in  times 
of  need  or  deprivation  any  one  of  the  first  three  divisions 
may,  in  a  way,  supply  the  place  of  either  of  the  other  two. 

Fothergill1  epitomizes  the  use  of  the  food-principles  in 
this  way  :  "  The  carbohydrates  are  the  body-fuel,  the  sur- 
plusage being  stored  as  fat;  the  albuminoids  (proteids) 
serve  to  repair  the  tissues  as  they  wear  out;  the  salts  form 
the  blood-salts;  the  fat  helps  to  bnild  up  normal  health 
tissues,  the  excess  being  burnt  as  body-fuel.  That  is  the 
real  object  of  food." 

While  in  the  main  correct,  this  is  a  broad  statement  of 
facts,  and  it  needs  some  qualification.  For  instance,  just 

i  Manual  of  Dietetics,  p.  5. 


182    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

as  there  is  some  wear  and  tear  in  any  mechanical  machine 
while  in  use,  which  must  eventually  be  provided  for;  so  in 
the  human  body  with  its  manifold  activities  there  must  be 
some  destructive  effect  upon  the  body  structure  and  tissue 
framework,  and  it  is  to  renew  and  replace  this  inevitable 
loss  of  material  that  a  part — perhaps  the  great  part — of  the 
proteid  food  is  taken.  But  we  now  also  know  that  in  addi- 
tion to  this  simple  repair  and  replacement  of  tissue,  "  the 
presence  of  nitrogenized  structure,  and  its  participation  in 
the  action  going  on  there,  is  a  necessary  condition  for  the 
manifestation  of  any  vital  energy  or  any  chemical  change," 
and  we  must  feel  that,  entirely  apart  from  the  idea,  of 
repair,  proteid  food  is  essential  to  the  maintenance  of  this 
chemical  and  vital  activity  of  nitrogenized  tissue. 

Confirming  this,  Pettenkofer  and  Yoigt  have  shown 
that  the  absorption  of  oxygen  is  largely  determined  by 
the  nitrogenous  substances  composing  the  tissues  of  the 
body,  and  that  it  is  proportional  to  their  size  and  vigor. 
Moreover,  it  is  known  that  proteids  may  be,  in  part,  con- 
verted into  fat  and  possibly  into  other  oxidizable  sub- 
stances, and  thus  become  a  source  of  body  heat  and  energy. 

So  also  with  the  fats  and  carbohydrates.  While  they 
are  not  immediately  nor  entirely  interconvertible,  and 
while  neither  class  may  be  permanently  excluded  from  the 
diet,  yet  in  emergency  either  may  apparently  fully  sup- 
plant and  substitute  the  other  for  a  time,  and  we  cannot 
yet  say  exactly  how  similar  or  dissimilar  their  service 
within  the  body  is. 

However,  while  FothergilPs  epitome  needs  this  emen- 
dation, known  facts  make  it  comparatively  easy  to  gain  a 
fair  idea  of  the  differences  and  functions  of  the  proximate 
food  principles,  to  which  end  some  help  will  probably  be 
given  by  the  following  table : 


FOOD, 


183 


!  EXAMPLES. 

,  1.  

FUNCTIONS. 

NITROGENOUS  SUBSTANCES. 

1.  Proteids. 

All  substances  containing  nitro- 
gen of  a  composition  identical 
with,  or  nearly  that  of  albumin  : 
proportion  of  N  to  C  being  nearly 
as  2  to  7,  or  4  to  14. 


1  (a).  Substances  containing  a 
larger  proportion  of  nitrogen  are 
apparently  less  nutritious. 

Proportion  of  N  to  C,  about  2  to 
5%,  or  4  to  11. 

(ft).  Extractive  matters,  such  as 
are  contained  in  the  juice  of  the 
flesh. 


NON-NITROGENOUS  SUBSTANCES. 
2.  Fats  (or  Hydrocarbon*). 

Substances  containing  no  nitro- 
gen, but  made  up  of  carbon,  hydro- 
gen, and  oxygen  ;  the  proportion 
of  oxygen  being  less  than  sufficient 
to  convert  all  the  hydrogens  into 
water. 

Proportion  of  unoxidized  H  to 
C,  about  1  to  7. 

3.  Carbohydrates. 

Substances  containing  no  nitro- 
gen, but  made  up  of  carbon,  hydro- 
gen, and  oxygen  ;  the  oxygen  be- 
ing exactly  sumcient  to  convert 
all  the  hydrogen  into  water. 

Proportion  of  water  to  carbon, 
about  3  to  2. 

3  (a).  Vegetable  acids  aiid pectous 
substances. 

Substances  containing  no  hydro- 
gen, but  made  up  of  carbon,  hydro- 
gen, and  oxygen  ;  the  oxygen  be- 
ing generally  in  greater  amount 
than  is  sufficient  to  convert  all  the 
hydrogen  into  water. 


4.  Salts  (mineral). 


Animal : 

Albumin,  ;    Formation  and  repair  of  tis- 

Fibrin,  sues  and  fluids  of  the  body. 

Syntqnin,  i    Regulation  of  the  absorption 

Myosin,  and  utilization  of  oxygen.  May 

Globulin,  also  form  fat  and  yield  energy 

Casein.  under  special  conditions.    In 

Vegetable  :  !  most  foods  the  above,  both  ani- 

Glutin,  mal  and  vegetable,  are  parti- 

Legumin.  ally  converted  into  peptones. 

Gelatin,  These    perform    the   above 

Ossein,  i  functions    less    perfectly,    or 

Chondrin,  '  only  under  particular  circum- 

Keratin,  stances. 


These  substances  appear  es- 
sential as  regulators  of  diges- 
tion and  assimilation,  especi- 
ally with  reference  to  the  gela- 
tin group. 


Olein,  Supply  of  fatty  tissues ;  nu 

Stearin,         trition    of    nervous    system  ? 

Margariu,      Supply  of  energy,  and  animal 

heat  by  oxidation. 


Starch,  Productive    of   energy  and 

Dextrin,  animal  heat  by  oxidation. 
Cane  sugar,  Conversion  into  fat  by  deoxi- 
Grape  "  |  dation. 
Lactin  (or 
milk  sugar) 


( More  O  than 
is  sufficient 

to  convert 

all  H  into 

H20). 

Oxalic  acid, 
Tartaric  " 
Citric 
Malic       " 
(No  excess 

of  O). 

Acetic  acid, 
Lactic  " 
Sodium 

chloride, 
Potassium 

chloride, 
Calcium 

phosphate, 
Magnesium 

phosphate. 
Iron,  etc. 


Preserving  the  alkalinity  of 
the  blood  by  conversion  into 
carbonates ;  furnish  a  small 
amount  of  energy  or  animal 
heat  by  oxidation. 


Various ;    support    of   bony 
skeleton,  supply  for  HC1  lor 
digestion,  etc.    Regulators  of 
!  energy  and  nutrition. 


184    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

Dietetics  means  "  a  systematic  regulation  of  the  diet  for 
hygienic  or  therapeutic  purposes. "  It  considers  all  the 
factors  that  affect  the  proper  digestion  and  assimilation  of 
food.  For  instance,  it  is  not  alone  necessary  to  determine 
just  what  substances,  in  a  chemical  sense,  the  body  needs 
to  sustain  life  and  maintain  health.  Nor  is  it  sufficient 
to  say  that  a  man  must  have  just  so  much  of  this  and  so 
much  of  that  food,  for  there  must  always  be  a  variation 
in  both  kind  and  quantity  to  meet  the  changing  demands 
of  the  system.  With  a  few  exceptions,  no  matter  how 
toothsome  or  healthful  a  certain  food  may  be,  it  soon  palls 
upon  the  appetite  if  necessity  compels  its  continued  use 
for  a  prolonged  period,  and  this  disgust  may  be  so  impressed 
upon  the  memory  of  the  senses  as  to  cause  them  to  prevent 
the  use  of  that  food  forever  after. 

The  aesthetic  factors  in  the  preparation  and  serving  of 
food  must  also  be  taken  into  account,  and  the  question  of 
pleasing  the  appetite  has  much  to  do  with  the  progress 
and  completeness  of  digestion.  Other  things  being  equal, 
palatable  and  agreeable  foods  are  disposed  of  much  more 
satisfactorily  than  others  not  so,  and  physicians  and 
others  should  learn  that  especially  in  sickness  the  appear- 
ance and  palatability  of  a  food  have  much  to  do  with  its 
acceptance,  not  only  by  the  patient,  but  by  his  stomach 
as  well.  Cleanness  and  neatness  in  food,  china,  and 
napery  are  of  greater  value  than  expense  or  show,  and  a 
little  attention  and  tact  in  such  matters  will  often  enable 
a  patient  to  take,  enjoy,  and  retain  food  and  nourish- 
ment, even  when  he  or  she  asserts  and  believes  this  to  be 
impossible. 

Another  factor  of  much  importance  in  the  digestion  of 
food,  but  one  too  often  too  lightly  considered,  is  the  mood 
or  state  of  mind  when  the  food  is  taken  and  while  it 


FOOD.  185 

remains  in  the  alimentary  canal.  There  is  more  than 
moral  philosophy  in  maintaining  a  cheerful  and  a  tranquil 
disposition  during  the  daily  meals  and  for  a  time  there- 
after; while  there  are  numerous  instances  of  most  serious 
results  occurring  from  the  giving  way  to  anger  or  other 
intense  emotion  at  such  times,  the  digestive  functions  being 
either  completely  checked  or,  what  is  frequently  worse,  so 
altered  that  the  products  are  actually  toxic  in  their  char- 
acter. And  is  not  a  dyspeptic  often  so  because  of  his 
pessimism,  rather  than  a  misanthrope  because  of  his  indi- 
gestion ? 

Before  proceeding  further  it  will  be  well  to  consider 
briefly  the  physiology  of  digestion  in  so  far  as  it  concerns 
the  chemical  changes  occurring  in  the  food  while  it  is  in 
the  digestive  tract.  These  changes  are  brought  about  by 
the  action  of  certain  bodies  secreted  or  made  by  the  diges- 
tive organs  and  glands,  which  we  have  been  in  the  habit 
of  calling  unorganized  ferments,  but  which  would,  perhaps, 
better  be  known  hereafter  as  enzymes.  Unorganized  fer- 
ments were  so  called  because  they  have  not  the  definite 
cell-formation,  life,  and  power  of  reproduction  which  be- 
long to  the  yeasts,  mould-fungi,  and  bacteria  which  bring 
about  the  fermentative  changes  in  organic  substances  so 
commonly  within  the  knowledge  of  every  one,  such  as  the 
conversion  of  saccharine  solutions  into  alcohol,  of  alcohol 
into  acetic  acid,  etc. 

The  enzymes  likewise  act  ujton  organic  matter,  viz. ,  upon 
the  food  which  we  eat,  and — like  the  other  ferments — ap- 
parently simply  by  their  presence  rather  than  by  entering 
into  actual  combination  with  the  matter  acted  upon,  as  do 
ordinary  chemical  reagents.  They  are  undoubtedly  the 
products  of  glandular  protoplasm,  probably  proteid  in 
nature,  and  some,  at  least,  very  likely  belonging  to  the 


186    ^  MANUAL  OF  HYGIENE  AND  SANITATION. 

group  of  nucleo-albumins,  which  latter  form  a  component 
part  of  every  organic  cell. 

The  knowledge  of  the  digestive  functions  will  be  greatly 
simplified  for  the  student  if  he  remembers  that  "  with  the 
possible  exception  of  the  coagulating  enzymes,  the  action  of 
the  enzymes  is  that  of  hydrating  agents:  they  produce 
their  effect  by  what  is  known  as  hydrolysis — that  is,  they 
cause  the  molecules  of  the  substance  upon  which  they  act 
to  take  up  one  or  more  molecules  of  water;  the  resulting 
molecule  then  splits  or  is  dissociated,  with  the  formation ' 
of  two  or  more  simpler  bodies. "l 

Thus  the  insoluble  proteids  and  carbohydrates  become 
respectively  the  soluble  peptones  and  sugars  of  their  allies, 
capable  of  absorption  into  the  myriad  capillaries  that  are 
distributed  throughout  the  lining  membrane  of  the  alimen- 
tary tract;  and  even  the  change  that  takes  place  in  the 
fat  digested  is  one  that  involves  the  taking  up  of  some 
water. 

There  are  four  characteristics  of  the  enzymes  worthy  of 
note  :  1.  That  they  are  all  soluble  in  water  and  glycerin, 
the  latter  being  specially  useful  in  making  stable  prepara- 
tions of  them  from  the  organs  producing  them.  2.  f(  That 
very  low  temperatures  (0°  C.)  retard  or  suspend  entirely 
their  action,  without,  however,  destroying  the  enzyme; 
that  for  each  enzyme  there  is  a  temperature  at  which  its 
action  is  greater/7  and  that  "  in  a  moist  condition  they 
are  all  destroyed  by  temperatures  below  the  boiling-point; 
60°  to  80°  C.  are  the  limits  actually  observed.772  3. 
"  That  they  never  completely  destroy  the  substance  upon 
which  they  act,77  probably  being  retarded  by  their  prod- 
ucts when  the  latter  reach  a  certain  percentage.  ' '  When 
these  are  removed  the  action  of  the  enzymes  begins  again.77 

i  American  Text-Book  of  Physiology,  first  edition,  p.  219.          2  Ibid. 


FOOD.  187 

4.  "  Except  for  very  small  quantities,  it  may  be  said  that 
the  amount  of  change  caused  is  independent  of  the  amount 
of  enzyme  present,7'  or  rather,  "  with  increasing  amounts 
of  enzymes  the  extent  of  action  also  increases,  reaching  a 
maximum  with  a  certain  percentage  of  enzyme;  increase 
of  enzyme  beyond  this  has  no  effect."  The  amount  of 
change  capable  of  being  produced  by  a  small  amount  of 
an  enzyme  is  enormous,  good  pepsin,  for  instance,  having 
the  power  of  converting  2500  times  its  own  weight  of 
proteid;  but  we  must  remember  that  this  power  is  not 
infinite,  and  that  after  a  time  all  of  the  enzymes  will  cease 
to  act. 

There  are  five  groups  or  classes  of  enzymes  to  be  found 
in  the1  animal  body  concerned  with  the  proper  digestion 
of  food,  and  it  is  interesting  to  note  that  examples  of 
each  of  these  classes  are  also  to  be  found  in  various  mem- 
bers of  the  vegetable  world.  The  two  principal  remaining 
classes,  being  neither  of  animal  origin  nor  digestive  agents, 
need  only  be  mentioned  here:  They  are  the  glucoside-split- 
ting  and  urea-splitting  enzymes,  the  latter  being  produced 
by  certain  bacteria  and  converting  urea  into  ammonium 
carbonate. 

Considering  the  digestive  processes  in  their  order  as  the 
food  proceeds  from  the  mouth  through  the  alimentary 
canal,  we  find  that  the  first  active  secretion  or  fluid  is  the 
saliva,  and  that  its  enzyme. is  ptyalin,  belonging  to  that 
group  which  converts  the  insoluble  carbohydrates  (starches) 
into  soluble  sugars,  maltose,  dextrin,  etc.  Pytalin  acts 
best  in  neutral  or  slightly  alkaline  media,  at  about  the 
body  temperature  (40°  C.),  and  upon  cooked  rather  than 
raw  starch.  Its  action  is  retarded  or  totally  checked  by  a 
low  temperature  or  by  strongly  alkaline  or  very  slightly 
acid  solutions,  and  the  enzyme  itself  is  actually  destroyed 


188    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

by  a  slight  increase  in  acidity  or  by  a  temperature  of  65° 
or  70°  C.  The  reason  it  converts  cooked  starch  so  much 
more  quickly  is  probably  because  the  heating  process  breaks 
up  the  cellulose  envelopes  that  protect  the  starch  granules 
within  from  its  action,  and  upon  which  the  pytalin  has 
almost  no  effect. 

In  addition  to  its  digestive  function,  the  saliva  also 
serves  to  moisten  dry  food  so  that  it  may  be  swallowed, 
and  to  dissolve  sapid  and  savory  substances  that  they  may 
be  duly  appreciated  by  the  organs  of  taste. 

Our  first  hygienic  lesson  in  regard  to  the  digestive 
functions  is,  therefore,  that  in  order  to  get  the  full 
benefit  of  the  salivary  secretions,  all  food,  and  especially 
that  of  a  starchy  nature,  should  be  well  masticated  and 
retained  in  the  mouth  for  some  little  time,  instead  of 
its  being  "  bolted"  at  once  or  after  a  hasty  bite  or 
two.  Nor  should  very  cold  nor  very  hot  beverages  be 
taken  at  the  same  time  with  the  food,  for  not  only  will 
the  action  of  the  pytalin  be  thus  retarded  or  destroyed, 
but  that  also,  as  we  shall  see,  of  the  gastric  juice  within 
the  stomach. 

The  food,  having  passed  from  the  mouth  to  the  stomach, 
may  still  be  acted  upon  for  a  few  moments  by  the  pytalin 
until  the  latter  is  checked  by  the  acid  of  the  gastric  juice. 
The  energy  of  digestive  action  is  then  transferred  from 
the  starches  to  the  proteid  constituents  of  the  food,  the 
chief  enzyme  now  being  pepsin,  though  we  also  find  in 
the  gastric  juice  a  coagulating  ferment — rennin,  which  acts 
upon  soluble  proteids  like  the  casein  of  milk,  to  form 
insoluble  clots  or  curds. 

Pepsin  acts  only  in  an  acid  medium  (the  acidity  being 
supplied  normally  by  the  free  hydrochloric  acid  of  the  gas- 
tric juice),  and  best  at  the  body  temperature.  As  stated, 


FOOD.  189 

extremes  of  temperature  are  adverse  to  its  activity,  and 
may  check  it  altogether,  and,  likewise,  too  much  or  too 
little  acid  may  have  the  same  effect,  from  0.2  to  0.3  per 
cent,  of  HC1  being  the  normal  amount  and  giving  the 
best  results.  Rennin  seems  in  the  normal  stomach  to  act 
only  on  the  casein  of  milk,  and  curdles  this  probably 
because  it  is  then  more  easily  digested  by  the  pepsin  and 
by  the  trypsin  of  the  pancreatic  juice. 

The  action  of  the  pepsin  plus  the  acid  upon  the  proteids 
of  the  food  is  a  hydrolytic  one,  and  the  end  products  are 
practically  hydrated  proteids,  substances  especially  diffusi- 
ble and  capable  of  absorption.  The  gastric  digestion,  there- 
fore, after  the  ptyalin  has  been  checked  by  the  acid  gastric 
juice,  practically  has  to  do  only  with  the  albuminous  or 
nitrogenous  part  of  the  food,  the  remainder,  or  at  least 
that  part  of  it  not  yet  capable  of  absorption,  remaining 
unchanged  until  it  passes  on  further  into  the  intestines. 
Soluble  salts,  sugars,  and  part,  at  least,  of  the  peptones  as 
they  are  formed,  may,  however,  be  taken  up  by  the  stom- 
ach capillaries,  while  the  rest  of  the  food-mass,  kept  ever 
in  motion  by  the  muscular  movements  of  the  stomach- 
walls,  is  being  thoroughly  mixed  and  converted  by  the 
peptic  action  into  the  semi-liquid  substance  called  chyme, 
which  is  passed  at  intervals  and  in  small  quantities  through 
the  pyloric  opening  into  the  .duodenum.  Long  before  the 
stomach  has  entirely  emptied  itself,  which  may  only  be 
after  several  hours  of  activity,  intestinal  digestion  is  well 
under  way,  and  in  some  respects  this  is  the  most  im- 
portant as  well  as  the  most  comprehensive  process  of  all. 
The  three  secretions  to  whose  combined  action  the  chyme 
is  now  subject  are  the  pancreatic  juice,  the  bile,  and 
the  intestinal  juice.  All  are  alkaline  and  quickly  neu- 
tralize the  gastric  acid;  it  scarcely  need  be  noted,  then, 


190    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

that  the  remaining  enzymes  act  best  or  only  in  alkaline 
media,  though  one  of  them,  trypsin,  may  act  in  solutions 
not  too  strongly  acid. 

In  the  pancreatic  juice  we  find  three  enzymes,  practically 
the  only  remaining  ones  of  much  importance;  although  in 
the  rather  scanty  intestinal  juice  two  others  have  been 
found,  one  capable  of  converting  starch  into  sugar,  and 
the  other  inverting  cane-sugar  into  levulose  and  dextrose. 
The  bile  contains  no  enzymes.  The  pancreatic  ferments 
are  trypsin,  which  acts  upon  proteids  and  albuminoids 
even  more  powerfully  than  pepsin,  and  likewise  converts 
them  into  peptones;  amylopsin,  which  is  practically  iden- 
tical in  its  properties  with  ptyalin;  and  steapsm,  which 
causes  neutral  fats  to  take  up  water  and  split  into  free 
fatty  acids  and  glycerin.  . 

Under  the  action  of  the  trypsin  all  that  portion  of  the 
proteid  foods  which  has  not  been  completely  digested  in 
the  stomach  reaches  that  stage  in  the  upper  intestines  and 
is  absorbed  therefrom.  In  fact,  it  is  very  probable  that 
the  tryptic  digestion  is  often  the  more  important  of  the 
two.  As  the  action  of  the  saliva  upon  the  carbohydrates, 
which  form  the  greater  bulk  of  our  food,  must  of  necessity 
be  very  limited,  it  is  evident  that  practically  almost  all 
of  the  starch  digestion  is  performed  by  the  amylopsin, 
aided  in  slight  measure  by  the  similar  enzyme  of  the  intes- 
tinal juice.  The  salts  and  other  soluble  elements  of  the 
food  have  already  been  absorbed,  and  there  remain  only 
the  fats  or  hydrocarbons. 

Under  the  influence  of  the  steapsin  comparatively  a 
small  portion  of  these  is,  as  stated,  separated  into  glyc- 
erin and  free  fatty  acids,  and  this  action  for  some  reason 
takes  place  much  more  rapidly  when  aided  by  the  bile 
than  with  the  pancreatic  juice  alone.  Then,  these  fatty 


FOOD.  191 

acids  unite  with  the  alkalies  and  alkaline  salts  of  the 
above  secretions,  but  especially  of  the  bile  and  intestinal 
juice,  to  form  soaps,  and  these  soaps  aid  in  emulsifying  the 
remainder  of  the  fats  and  thus  making  them  ready  for 
absorption,  which  latter  process  is  also  facilitated  by  the 
direct  action  of  the  bile  upon  the  intestinal  epithelium. 

The  digestive  processes  having  been  thus  outlined,  it 
will  be  well  to  learn  how  they  may  be  maintained  as  com- 
plete and  perfect  as  possible.  In  the  first  place,  the  cook- 
ing of  food  is  usually  an  essential  preliminary.  We  cook 
meats  not  only  to  make  them  more  agreeable  to  the  palate, 
but  also  to  facilitate  digestion.  The  effect  of  cooking  upon 
muscle  (flesh)  is  "  to  loosen  the  bundles  of  fibrillae  from 
each  other,  so  that  they  are  readily  torn  asunder  or  crushed 
by  the  teeth,"  while  the  various  connective  tissues  are 
softened  and  gelatinized,  not  only  thus  becoming  more 
digestible  and  nutritious,  but  allowing  the  histologic  ele- 
ments which  they  bind  together  to  separate  and  be  more 
freely  acted  upon  by  the  solvent  fluids.  So  with  the 
vegetables,  the  heat  and  steam  soften  and  rupture  the 
cellulose  envelopes  of  the  various  cells  that  the  ferments 
may  the  more  readily  act  upon  their  contents;  and  at  the 
same  time  they  bring  about  subtle  chemical  changes  that 
greatly  increase  the  palatability  of  the  food-stuffs. 

Thorough  mastication  of  the  food  is  important  for  the 
reasons  already  stated,  and  the  cause  of  most  dyspepsias 
may  be  found  in  faulty  habits  of  eating.  Foster  says  that 
in  the  stomach  "  the  natural  bundles  of  meat  and  vegeta- 
bles fall  asunder,  the  muscular  fibres  split  up  into  disks, 
and  the  protoplasm  is  dissolved  from  the  vegetable  cells ;" 
but,  "  if  the  meat  be  not  chewed  properly,  but  '  bolted/ 
the  solvent  gastric  juice  can  only  act  on  the  exterior  of  the 
mass,  while  l  lumps '  offend  the  stomach  and  arrest  the 


192    ^  MANUAL  OF  HYGIENE  AND  SANITATION. 

gastric  secretion."  The  importance  of  abstaining  at  meal- 
time from  beverages  or  other  substances  of  too  low  or  too 
high  a  temperature  has  already  been  stated,  and,  as  ail  the 
enzymes  act  best  at  the  body  temperature,  care  should 
always  be  had  to  avoid  the  chilling  of  the  abdominal 
organs  while  digestion  is  under  way. 

Again,  as  the  formation  and  action  of  the  enzymes  begin 
with  the  ingestion  of  food  and  depend  largely  upon  a 
sufficient  blood-supply  to  the  organs  concerned  as  long  as 
digestion  continues,  it  is  essential  that  the  blood-current 
shall  not  be  diverted  from  these  organs  during  this  period 
by  excessive  mental  or  physical  demands,  and  that  a  con- 
dition of  cheerfulness,  repose,  and  rest  should  wisely  follow 
every  meal.  Regularity  as  to  the  time  of  meals  and  the 
avoidance  of  too  great  a  tax  upon  any  of  the  organs  by 
over-indulgence  or  intemperance  in  eating  are  likewise 
both  important  matters  and  ones  too  often  neglected. 

It  is  interesting  to  note  that  in  certain  members  of  the 
vegetable  kingdom  are  to  be  found  enzymes  very  similar 
to  those  just  considered,  and  that  where  the  latter  appear 
to  be  deficient  in  quantity  or  action,  these  kindred  ones 
may  be  used  with  advantage.  Thus,  in  the  pineapple 
and  in  the  papaw  are  ferments  akin  to  pepsin  or  trypsin, 
and  in  the  former  another  with  the  same  action  as  rennin. 
All  are  familiar  with  the  diastase  of  germinating  seeds 
and  its  use  in  the  making  of  beer,  but  not  so  common 
is  the  knowledge  that  other  seeds  contain  fat-splitting 
enzymes  much  like  steapsin. 

The  Amount  of  Food  Necessary  to  Life  and  Health. 
Considerable  work  has  been  done  to  determine  just  what 
amount  of  the  proximate  food  principles  the  average  per- 
son requires  daily,  and  in  this  respect  Moleschott's  tables 
are  quite  generally,  accepted,  having  been  constructed  from 


FOOD.  193 

data  gained  by  actual  experiment  and  also  by  the  con- 
tinued observation  of  the  effects  of  a  number  of  dietaries. 
According  to  these  tables,  a  man  weighing  160  pounds 
and  doing  work  equivalent  to  300  foot-tons  per  diem  will 
need  about  4.6  ounces  of  proteids,  3  ounces  of  fats,  14.25 
ounces  of  carbohydrates,  and  a  little  more  than  1  ounce  of 
salts.  Prof.  Yaughan  believes  that  the  average  working 
man  in  America  requires  daily,  in  round  numbers,  not 
less  than  four  ounces  of  proteids,  two  ounces  of  fats,  and 
eighteen  ounces  of  carbohydrates. 

It  is  essential  that  the  proper  proportion  between  the 
ingested  nitrogen  and  carbon  should  be  maintained,  and 
this  should  be  as  one  of  the  former  to  fifteen  of  the  latter. 

In  addition,  the  individual  needs  from  70  to  100  fluid- 
ounces  of  water  daily,  a  good  part  of  which,  however,  is 
normally  taken  with  the  food.  It  must  be  remembered 
that  the  above  figures  only  represent  average  amounts,  and 
that  climate,  amount  of  exercise,  the  size  and  activity  of 
functional  and  excretory  organs,  and  personal  peculiarities 
all  serve  to  modify  them  in  the  case  of  any  special  indi- 
vidual. 

Other  conditions  not  interfering  too  greatly,  any  combi- 
nation of  foods  giving  the  above  amounts  of  the  proximate 
principles  at  a  reasonable  cost  will  be  an  economical 
and  healthy  diet,  provided  such  food  is  acceptable  to  the 
palate,  is  digestible,  and  contains  nothing  harmful  to  the 
system.1 

Fothergill  thinks  that,  as  a  rule,  we  take  too  much  pro- 
teid  food,  especially  in  the  form  of  meat,  and  that,  though 
this  goes  in  the  main  for  tissue  repair,  the  latter  requires 

1  For  such  combinations,  see  Vaughan's  Healthy  Homes  and  Foods  for  the 
Working  Classes,  and  Mrs.  Abel's  Practical,  Sanitary,  and  Economic  Cooking. 
Both  are  essays  published  by  the  American  Public  Health  Association. 

13 


194-4  MANUAL  OF  HYGIENE  AND  SANITATION. 

much  less  of  such  food  than  we  ordinarily  suppose,  and 
that  the  system  does  not  need  so  very  much  of  albumin  or 
its  equivalents.  In  this  he  may  be  correct  to  a  certain 
degree,  particularly  as  regards  his  fellow-Englishmen, 
who  are  notorious  meat  eaters,  and  as  to  the  facts  that 
tissue  waste  is  comparatively  slight,  and  that  the  body 
framework  rusts  out  rather  than  burns  out.  But  in  addi- 
tion to  the  statements  already  made— »- that  part  of  our  nitro- 
genous food  regulates  the  demand  for  oxygen  and  that 
part  is  doubtless  a  source  of  energy  and  may  be  converted 
into  fat — we  should  also  remember  that  animal  food  is  a 
concentrated  food,  that  much  energy  has  been  expended  in 
converting  and  storing  it  up  from  the  vegetable  world, 
that  it  is  stimulating,  and  that  our  digestive  organs  resem- 
ble more  closely,  at  least  as  far  as  comparative  weight  is 
concerned,  those  of  the  carnivora  rather  than  of  the  herbiv- 
ora.  These  reasons,  as  well  as  the  fact  that  proteids  make 
up  a  considerable  part  of  the  only  typically  complete  food 
that  we  have  and  which  nature  gives  to  the  mammalian 
infant,  indicate  that  we  should  be  as  careful  not  to  use  too 
little  as  too  much  nitrogenous  food. 

The  proteid  portion  of  our  food  is  obtained  from  the 
albumin  of  meat  and  fish,  from  milk  and  eggs,  and  from 
the  gluten  of  cereals  and  the  vegetable  casein  (albumin) 
of  the  leguminous  plants,  such  as  peas,  beans,  etc.  The 
proportion  and  properties  of  the  albuminous  matter  vary, 
of  course,  in  each  of  these,  and  even  in  the  same  substances 
under  different  circumstances;  but  all  should  be  taken  into 
consideration  and  used  interchangeably,  if  we  wish  to 
obtain  the  greatest  variety  and  benefit  in  feeding,  together 
with  due  economy  of  expense. 

In  this  connection  attention  may  be  directed  to  the 
peculiar  fact  that  the  leguminous  plants,  through  the  aid 


FOOD.  195 

of  certain  species  of  bacteria,  are  able  to  absorb  and  store 
up  in  the  form  of  proteids  a  considerable  quantity  of 
nitrogen  from  the  surrounding  atmosphere. 

The  carbohydrates  that  furnish  food  to  the  body  and  are 
one  of  the  sources  of  the  heat  and  energy  upon  which  mus- 
cular motion  and  vital  activity  depend,  are  practically  all 
derived,  with  the  exception  of  milk  sugar,  from  the 
starches,  sugars,  and  gums  of  the  vegetable  kingdom. 

It  has  already  been  shown  that  much  the  greater  part 
of  the  digestion  of  carbohydrate  food  is  due  to  the  action 
of  the  pancreatic  enzyme — amylopsin,  but  we  should  not 
forget  the  action  of  the  saliva,  nor  that  thorough  mastica- 
tion greatly  assists  the  subsequent  digestion  by  breaking 
up  the  starch  granules  and  exposing  them  more  freely  to 
the  action  of  the  digestive  juices.  The  latter  object  is  also 
obtained  by  crushing  the  cereals,  and  by  cooking  the 
starch-bearing  foods,  for  "  grinding  and  cooking  lessen 
the  labor  of  the  jaws  and  salivary  (and  pancreatic)  glands." 

After  the  end-products  (dextrose,  levulose,  etc.)  of  car- 
bohydrate digestion  have  been  absorbed  from  the  alimen- 
tary canal,  part  of  them,  at  least,  are  reconverted  in  the 
liver  into  animal  starch  or  glycogen,  and  this  portion 
becomes  a  part  of  the  body-store  of  fuel.  Fothergill  says : 
"  The  liver  stores  up  from  each  meal  so  much  glycogen 
and  gives  it  off  as  required;  otherwise  life  would  only  be 
one  dreary  meal."  Another  and  perhaps  greater  moiety 
of  the  digested  carbohydrates  is  converted  into  fat  and 
stored  away  as  adipose  tissue  in  various  parts  of  the  body, 
a  further  reserve  of  fuel  for  any  emergency.  (t  Many 
authorities  state  that  fat  is  formed  directly  from  carbohy- 
drates, and  the  weight  of  evidence  appears  to  favor  this 
view;  but  whether  it  is  so  formed  directly,  or  indirectly 
by  retarding  the  metabolism  of  the  fatty  and  proteid  con- 


196    A  MANUAL  GF  HYGIENE  AND  SANITATION. 

stituents  of  the  food,  there  is  no  doubt  that  the  consump- 
tion of  carbohydrates  results  in  the  formation  of  fat  within 
the  body."  Moreover,  "whatever  the  mixture  of  fats 
taken  in  as  food,  the  fat  of  the  body  always  has  the  same 
composition;  this  fact  agrees  with  the  conclusion  that  the 
metabolism  and  deposition  of  fat  in  the  body  is  due  to  cell 
activity,  and  that  the  fat  comes  in  part  from  the  proteid 
and  part  from  the  carbohydrate  foods."2 

Another  important  function  of  the  carbohydrate  foods 
is  the  formation  by  their  metabolism  in  the  body  of  lactic 
and  other  acids,  which  are  of  the  greatest  value  in  nutri- 
tion and  in  maintaining  the  normal  reactions  of  the  body- 
fluids.  This  is  perhaps  one  of  the  chief  reasons  why  fats 
and  carbohydrates  are  not  interconvertible  in  any  pro- 
longed dietary. 

Fat  is  essentially  a  compound  of  glycerin  with  one  or 
more  fatty  acids,  usually  stearic,  palmitic,  and  oleic.  The 
digestibility  of  a  fat  largely  depends  upon  its  being  fluid 
at  the  body  temperature;  therefore,  the  more  stearine, 
whose  melting-point  is  higher  than  this,  a  fat  contains,  the 
less  digestible  it  will  be.  For  this  reason  butter  is  more 
digestible  than  suet,  lard  than  mutton  fat,  etc.,  and  the 
more  easily  assimilable  cod-liver  oil  is  that  from  which 
the  stearine  has  been  removed. 

Fat  for  food  is  derived  from  vegetable  as  well  as  animal 
sources,  many  seeds  and  nuts  and  some  cereals,  as  oats  and 
corn  (maize),  containing  much  fat.  By  improved  methods 
it  is  becoming  possible  to  supply  fats  in  purer,  cheaper, 
and  more  agreeable  forms,  so  that  they  can  now  be  freely 
used  even  by  the  poor,  the  very  class  that  needs  them  most. 

Under  normal  conditions  it  is  probable  that  the  body-fat 

1  Notter  and  Firth :  Treatise  on  Hygiene,  p.  254.  -  Ibid.,  p.  253. 


FOOD.  197 

or  adipose  tissue  is  almost  never  derived  from  the  fat  in 
food,  but  rather,  as  stated,  from  the  proteids  and  carbohy- 
drates. But  fat  is  also  an  essential  part  of  tissue-struc- 
ture, making  up  more  than  one-fifth  of  the  solid  matter  of 
the  brain  and  one-sixth  of  muscle,  and  possibly  serving 
as  fuel  when  the  tissue  is  oxidized;  and  it  is  not  impossible 
that  this  tissue  fat  may  come  in  part  from  that  ingested  as 
food.  The  writer  has  already  hinted  at  the  possibility  of 
a  combination  of  the  newly  absorbed  fat  with  the  argon 
of  the  atmosphere  in  the  lungs,  and  the  consequent  forma- 
tion of  new  cells  or  vital  material.  In  any  case,  how- 
ever, fat  is  a  very  necessary  part  of  a  man's  diet,  for  not 
only  is  a  small  quantity  necessary  to  the  digestion  of  pro- 
teids, causing  the  formation  in  the  body  of  larger  amounts 
of  fat  than  the  quantity  ingested  and  greatly  improving 
the  physical  condition;  but  it  may  be,  and  undoubtedly 
often  is,  used  directly  as  fuel  when  occasion  requires 
without  first  being  stored  up  in  the  tissues.  As  it  is  a 
concentrated  fuel-food,  it  is  to  be  used  freely  when  we 
want  to  keep  the  body  warm  or  when  we  need  extra  force 
for  any  increased  exertion. 

"  On  a  diet  rich  in  fat  great  muscular  effort  can  be 
undergone  with  but  little  destruction  of  muscular  tissue, 
and  without  increased  urea  discharge."  The  object  of  fat 
in  the  diet,  then,  may  be  said  to  be  as  fuel  to  give  heat 
and  energy,  and,  when  necessary,  to  aid  in  the  repair  or 
building  up  of  active  tissue. 

The  constructive  property  of  fat  is  especially  valuable 
in  the  treatment  of  all  wasting  diseases,  especially  phthisis. 
Fothergill  emphatically  declares  that  l '  the  great  food  for 
the  strumous  is  fat,"  and  also  says:  "Whenever  there 
is  any  tendency  to  tubercle  the  individual  should  learn 
to  eat  fat,  just  as  a  seafaring  man  learns  to  swim.  As  a 


198    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

physician  to  a  chest  hospital  I  have  learned  to  dread  the 
announcement  that  fat  is  no  longer  taken,  especially  if  the 
individual  is  of  strumous  build,  with  a  small,  narrow 
chest.  In  my  opinion,  the  existence  of  a  considerable  area 
of  affected  lung  where  the  digestive  powers  keep  up  is  less 
fraught  with  evil  and  less  prognostically  significant  than 
intractable  wasting  with  very  little  disease  in  the  lung." 
In  this  connection,  note  that  an  excess  of  proteids  in  the 
diet  causes  a  more  rapid  oxidation  of  fat,  and  that  an 
excess  of  fat  or  of  carbohydrates  lessens  the  absorption  of 
oxygen  and  the  oxidation  of  both  fats  and  proteids.  Also, 
that  the  free  use  of  fluids  is  thought  to  favor  an  increase 
in  the  quantity  of  fat  deposited  in  the  body. 

Fat  is  practically  indigestible  in  the  stomach,  and  some 
stomachs  cannot  tolerate  it,  especially  when  taken  with 
other  food ;  although  usually  a  little  fat  assists  in  the  diges- 
tion of  proteids  by  stimulating  the  secretion  of  the  gastric 
juice.  Cases  occur  not  rarely  in  which  it  is  necessary  that 
comparatively  large  quantities  of  fat  should  be  ingested 
and  yet  in  which  there  is  apparently  decided  gastric  intol- 
erance of  it.  In  such  event  success  is  often  to  be  attained 
by  giving  the  fat  some  little  time  after  the  regular  meals, 
when  the  gastric  digestion  is  approaching  completion  and 
the  chyme  is  being  passed  out  of  the  stomach  to  be  further 
subjected  to  the  action  of  the  intestinal  digestants.  It 
may  also  be  well  to  emulsify  it  partially  or  wholly,  espe- 
cially if  there  be  faulty  secretion  of  bile  and  pancreatic 
juice,  and  sometimes  to  disguise  its  taste  with  agreeable 
flavors.  In  this  way  there  is  generally  but  little  trouble 
in  administering  fats,  even  such  as  those  which,  like  cod- 
liver  oil,  have  a  disagreeable  taste  and  odor.  Failing  in 
this,  we  may  still  resort  to  inunctions,  preferably  of  pre- 
digested  or  emulsified  fats,  and  often  with  considerable 


FOOD.  199 

advantage,  since  it  has  been  experimentally  shown  that 
after  passing  through  the  skin  fat  may  be  taken  up  by  the 
subcutaneous  lymphatics  and  later  be  oxidized  or  meta- 
bolized almost  as  completely  as  if  it  had  entered  the 
system  by  way  of  the  intestinal  canal  and  thoracic  duct. 

Certain  salts  in  certain  proportions  are  necessary  for 
the  maintenance  of  health  in  the  body.  "  Lime,  chiefly 
in  the  form  of  phosphate,  is  absent  from  no  tissue,  and 
there  is  reason  to  think  that  no  cell-growth  can  go  on 
without  it."  Even  the  bacteria  must  have  earthy  phos- 
phates for  the  purposes  of  growth.  Chlorine,  derived 
largely  from  the  sodium  chloride  of  food,  is  necessary  to 
form  the  hydrochloric  acid  of  the  gastric  juice,  the  chlo- 
rides also  keeping  in  solution  the  globulins  of  the  blood 
and  body  fluids  and  helping  to  dissolve  the  albumin. 
Phosphorus  is  necessary  in  the  formation  of  the  lecithin 
of  nerve  tissues,  as  well  as  for  the  phosphates  above  men- 
tioned, and  those  of  potassium,  magnesium,  etc.,  which  go 
to  form  bone.  Potash  salts  maintain  the  alkalinity  of  the 
solid  tissues,  and  soda  salts  that  of  the  body  fluids.  Iron 
is  essential  for  the  construction  and  nutrition  of  the  blood- 
corpuscles,  though  small  quantities  of  it  are  to  be  found 
in  almost  every  other  tissue. 

But  not  only  must  the  above  inorganic  salts  be  given  in 
proper  supply,  but  also  certain  ones  of  organic  nature,  in 
order  to  prevent  conditions  of  malnutrition  or  disease. 
Those  especially  which  are  changed  to  form  carbonates,  as 
the  lactates,  tartrates,  etc.,  or  their  respective  acids,  help  to 
maintain  the  alkalinity  of  the  system  and  appear  to  be 
most  essential,  as  a  scorbutic  condition  seems  to  be  inevi- 
tably created  or  fostered  by  their  absence.  There  is  also 
some  evidence  that  certain  gouty  conditions  may  be  due 
to  the  removal  of  the  natural  vegetable  salts  by  unwise 


200    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

methods  of  cooking.  The  fact  of  the  carbohydrates  being 
an  important  source  of  these  organic  acids  and  salts  has 
already  been  mentioned. 

Lastly,  with  many  of  our  foods  we  require  the  addition 
of  certain  flavors,  condiments,  etc.,  which,  though  they 
have  little  or  no  real  food  value  in  themselves  in  the  sense 
of  repairing  tissue  or  furnishing  energy,  do  much  good, 
when  not  abused,  by  making  the  food  more  palatable,  by 
stimulating  the  secretion  of  the  digestive  fluids,  and  by 
acting  as  carminatives.  These  condiments  should  not  be 
omitted  from  the  food  of  the  sick  or  convalescent,  for  they 
have  a  value  of  their  own,  and  are  il  agreeable  to  the  palate 
and,  in  moderation,  good  for  the  digestive  organs/' 

As  a  review  of  the  preceding  statements,  the  following 
quotation,  from  Notter  and  Firth,1  may  be  of  value  : 

"  With  regard  to  the  necessity  for  all  four  classes  of 
aliments,  it  can  be  affirmed  with  certainty  that  (putting 
scurvy  out  of  the  question)  men  can  live  for  some  time 
and  can  be  healthy  with  a  diet  of  proteids,  fats,  salts,  and 
water.  But  special  conditions  of  life,  such  as  great  exer- 
cise or  exposure  to  very  low  temperature,  appear  to  be 
necessary,  and  Under  usual  conditions  of  life  health  is  not 
very  perfectly  maintained  on  such  a  diet.  It  has  not  yet 
been  shown  that  men  can  live  in  good  health  on  proteids, 
carbohydrates,  salts,  and  water,  etc.,  without  fat. 

"  The  exact  effect  produced  by  the  deprivation  of  any  one 
of  these  classes  is  not  yet  known.  An  excess  of  the  pro- 
teids causes  a  more  rapid  oxidation  of  fat,  while  an  excess 
of  fat  lessens  the  absorption  of  oxygen,  and  hinders  the 
metamorphosis  of  both  fat  and  albuminous  tissues.  The 
carbohydrates  have  the  same  effect  when  in  excess,  and 
appear  to  lessen  the  oxidation  of  the  two  other  classes. 

1  Treatise  ou  Hygiene,  p.  256. 


FOOD.  201 

u  It  is  generally  admitted  that  the  success  of  Banting's 
treatment  of  obesity  is  owing  to  two  actions  :  the  increased 
oxidizing  effect  on  fat  consequent  on  the  increase  of  meat 
(especially  if  exercise  be  combined),  and  the  lessened 
interference  with  the  oxidation  of  fat  consequent  on  the 
deprivation  of  starches. 

"  Health  cannot  be  maintained  on  proteids,  salts,  and 
water  alone;  but,  on  the  other  hand,  it  cannot  be  main- 
tained without  them/' 

It  will  be  impossible  to  go  into  details  concerning  all 
the  articles  commonly  used  as  foods,  but  there  are  certain 
facts  that  should  be  well  known  and  which  cannot  prop- 
erly be  omitted  from  a  work  of  this  kind. 

Milk  is  a  typical  food-stuff,  complete  in  itself,  in  that  it 
contains  all  the  food  principles,  and  these  in  nearly  the 
proper  proportion,  at  least  for  infant  life.  The  casein  and 
albumin  represent  the  proteids;  the  cream,  the  fats;  and  the 
lactose  or  milk-sugar  is  a  concentrated  carbohydrate — all 
being  in  combination  with  sufficient  salts  and  water. 

It  should  constitute  almost  the  sole  food  of  infants  during 
the  earlier  months  of  life;  and  that  it  is  capable  of  sustain- 
ing adult  life  almost  indefinitely,  especially  where  there  is 
little  demand  for  heat  or  the  expenditure  of  force,  has  been 
shown  in  numerous  instances.  •  Coplin  and  Bevan  mention 
the  case  of  a  patient  who  lived  and  thrived  on  milk  alone 
for  over  thirteen  months,  and  of  another  who  lived  for 
three  years  on  the  same  diet.  But,  of  course,  the  limited 
proportion  of  carbohydrates,  even  though  concentrated,  is 
not  all-sufficient  for  the  maintenance  of  great  vital  activity, 
and  for  persons  in  ordinary  life  some  addition  to  the  diet 
is  necessary. 

The  albumin  of  milk  is  coagulated  by  heat,  but  the 
casein,  which  constitutes  the  greater  part  of  the  proteid 


202    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

element,  is  clotted  by  an  acid  or  by  an  enzyme,  such  as 
rennin ;  and  as  both  of  these  are  present  in  normal  gastric 
juice,  it  would  seem  that  the  preliminary  coagulation  of 
casein  was  essential  to  its  proper  digestion.  It  should  be 
remembered,  however,  that  the  casein  of  cow's  milk  forms 
a  much  harder  and  firmer  clot  than  does  that  of  human 
milk,  and  that  the  former  should,  therefore,  never  be 
introduced  into  the  stomach  in  large  volumes,  but  should 
rather  be  taken  slowly  and  preferably  with  other  food 
which  will  help  to  divide  the  curd  mechanically.  In  the 
feeding  of  children  an  alkali,  such  as  lime-water,  mixed 
with  the  milk  is  thought  to  soften  the  curd  and  possibly 
facilitate  digestion. 

Outside  of  the  body,  fermentative  changes  due  to  certain 
bacteria  may  convert  the  milk-sugar  into  lactic  acid,  which 
coagulates  the  casein  and  ((  sours "  the  milk.  Another 
peculiarity  of  casein  is  the  tenacity  with  which  it  holds 
large  quantities  of  phosphate  of  lime,  one  of  the  most 
valuable  of  food-salts. 

Sometimes  it  is  advantageous  or  necessary  to  predigest 
milk  for  infants  or  sick  persons,  but  if  the  digestion  be 
carried  beyond  a  certain  point,  the  consequent  peptones 
and  albumoses  will  give  the  milk  a  bitter  and  disagreeable 
taste.  In  the  feeding  of  infants  it  must  not  be  forgotten 
that  the  percentage  composition  of  human  milk  is  different 
from  that  of  cow's  milk,  and  that  the  latter  will  need  dilu- 
tion to  decrease  the  proteid  proportion,  but  an  increase  of 
fat  and  carbohydrates.  As  a  child  grows  older  and  more 
active,  it  becomes  necessary  to  add  to  the  milk  additional 
carbohydrates.  These  should  be  easy  of  digestion  and 
soluble,  milk-sugar  and  predigested  starches  in  the  form 
of  maltose  an,d  its  allies  being  preferable. 

Milk  should  always  be  kept  as  cool  as  possible  and  in 


FOOD.  203 

closed  vessels,  not  only  to  prevent  the  absorption  of  dis- 
agreeable odors  and  harmful  gases,  to  which  it  is  very 
prone,  but  to  exclude  dirt  and  bacteria.  As  it  is  an  excel- 
lent culture  medium,  and  as  it  is  commonly  liable  to  be 
exposed  to  contamination  by  organisms  from  many  sources 
before  it  reaches  the  consumer,  fermentative  or  other 
harmful  chemical  changes  are  almost  certain  to  occur  in 
it  if  the  temperature  conditions  are  at  all  favorable.  For 
this  reason,  it  is  necessary  that  the  greatest  care  should  be 
used  in  the  handling  of  the  milk  from  the  time  it  leaves 
the  cow  until  it  is  used,  and  for  the  feeding  of  children 
and  whenever  there  is  any  possibility  of  it  being  the  car- 
rier of  disease  germs  of  any  kind,  it  should  be  properly 
sterilized  and  then  kept  sterile  until  used.  In  fact,  steril- 
ized milk,  modified  to  resemble  the  human  secretion,  will 
usually  be  superior  to  any  other  artificial  food  for  infants, 
but  the  sterilization  should  always  be  done  before  fermenta- 
tion has  begun  and  harmful  products  have  been  developed 
in  the  milk.  The  sterilization  may  slightly  alter  the  taste 
and  other  properties  of  the  milk  by  coagulating  the  albu- 
min, bat  it  is  doubtful  whether  it  makes  any  real  change 
in  its  digestibility. 

The  cream  of  milk  is  fat  in  its  most  digestible  and 
acceptable  form,  and  should  not  be  removed  from  milk  if 
the  latter  is  to  be  used  as  food.  If  the  milk  seems  to  be 
too  rich,  it  may  be  advisable  to  skim  it,  giving  it  in  some 
form  or  other  with  the  regular  meal  and  reserving  the 
cream  until  a  couple  of  hours  or  so  later,  when  gastric 
digestion  is  approaching  completion.  One  may  also  often 
escape  the  use  of  cod-liver  oil  and  similar  fats  by  taking 
cream  in  this  way — either  plain  or  flavored  and  whipped 
— some  little  time  after  the  meals. 

Skimmed  milk  and  buttermilk  may  be  used  freely  as 


204    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

beverages,  as  both  are  refreshing  and  healthful,  with  some 
food  value;  buttermilk  is  also  very  acceptable  to  many 
persons  on  account  of  its  lactic  acid.  "  Koumiss "  and 
"  kefir  "  are  both  prepared  from  milk  through  the  action 
of  certain  fermentative  organisms,  which  also  bring  about 
a  partial  digestion  of  the  casein.  Each  contains  carbonic 
and  lactic  acids,  though  in  different  proportions,  some  pep- 
tones or  albumoses,  and  a  little  alcohol.  They  are  agree- 
able to  most  palates  and  are  usually  retained  and  utilized 
by  stomachs  rebellious  to  almost  all  other  foods. 

Milk  may  be  a  factor  in  the  causation  of  disease  in  a 
number  of  ways.  The  products  of  the  fermentative  action 
already  referred  to  are  a  frequent  source  of  serious  intes- 
tinal disorders  in  infants  and  even  in  adults;  while  if 
further  decomposition  occurs,  a  very  poisonous  ptomaine, 
called  tyrotoxicon,  is  apt  to  be  developed  and  to  cause 
even  fatal  results  to  those  using  the  milk.  This  same 
substance  is  also  liable  to  occur  in  any  milk-product,  such 
as  cheese  or  ice-cream,  and  is  usually  the  cause  or  agent 
in  the  cases  of  poisoning  by  such  products  that  are  so 
frequently  reported. 

Again,  the  active  principles  of  plants  which  the  cow  has 
eaten  may  be  transmitted  by  the  milk  and  produce  their 
physiological  effects.  But  a  graver  question  is  whether 
disease  may  be  transmitted  directly  from  the  animals  to 
man  by  this  almost  universal  food-stuff.  Every  one  knows 
that  the  milk  from  sick  cows  may  cause  marked  disturb- 
ance of  health,  and  there  now  seems  to  be  fair  evidence 
that  cattle  are  subject  to  certain  diseases  identical  with  or 
very  similar  to  human  maladies,  the  milk  serving  as  a 
carrier  for  the  contagium. 

Scarlet  fever  and  diphtheria  may  be  mentioned  as  dis- 
eases suspected  of  being  transmitted  in  this  way,  and  there 


FOOD.  *  205 

is  no  longer  any  doubt  in  regard  to  tuberculosis.  Though 
some  authorities  still  question  whether  this  disease  can  be 
thus  transmitted  unless  the  milk-glands  themselves  are 
affected,  the  great  prevalence  of  the  disease  among  cattle 
and  experimental  evidence  both  make  it  certain  that  milk 
is  often  tuberculous,  and  many  believe  that  by  far  the 
larger  number  of  the  many  cases  of  infantile  tuberculosis 
have  origin  from  this  source. 

Milk  may  also  become  a  disease  carrier  through  care- 
lessness in  handling  by  infected  persons  or  by  the  admix- 
ture with  it  of  water  containing  disease  germs.  Epidemics 
of  diphtheria,  scarlet  fever,  typhoid  fever,  and  cholera 
have  all  been  traced  to  a  contaminated  milk-supply,  and 
it  is  a  question  whether  many  of  the  more  or  less  local 
outbreaks  in  cities  are  not  of  this  character.  The  writer 
is  personally  cognizant  of  five  cases  of  undoubted  scarlet 
fever  that  occurred  almost  simultaneously  in  one  locality 
and  in  which,  apparently,  the  only  common  source  was  the 
milk-supply.  He  was  unable  to  discover  that  there  had 
been  any  illness  either  among  the  cattle  or  in  the  family  of 
the  milkman  in  question,  but  he  has  always  felt  that  there 
was  considerable  evasion  in  replying  to  the  inquiries  made. 

The  possibility  of  milk  as  a  source  of  danger  to  health 
having  been  shown,  the  lessons  to  be  had  are  these:  that 
not  only  must  there  be  the  greatest  care  in  the  handling 
and  keeping  of  milk  until  it  is  consumed,  but  there  must 
also  be  frequent  and  careful  inspection  of  the  animals 
from  which  it  comes  and  of  their  environment;  that  no 
milk  from  any  diseased  cow  should  ever  be  used  as  food; 
that  wherever  there  is  the  suspicion  or  possibility  of  the 
milk  being  contaminated  with  disease  germs,  it  must  be 
thoroughly  sterilized,  and  that  any  change  from  its  normal 
condition  should  also  forbid  its  use. 


206     A  MANUAL  OF  HYGIENE  AND  SANITATION. 

Fortunately,  good  milk  can  almost  always  be  had  so 
cheaply  and  readily  that  no  serious  hardship  inures  in  the 
strict  observance  of  these  rules,  and  the  public  should  be 
educated  to  demand  as  well  as  fairly  to  pay  for  pure  milk 
from  healthy  animals,  these  matters  being  even  more  im- 
portant than  that  the  quality,  as  shown  by  analysis,  should 
always  be  up  to  a  certain  standard. 

Good  milk  in  balk  should  be  opaque,  of  clean  ivory- 
white  color,  should  have  no  peculiar  smell  or  taste  nor 
any  deposit  on  standing.  Nor  should  it  show  any  change 
in  taste  or  appearance  upon  boiling,  excepting  the  forma- 
tion of  the  slight  skin  of  coagulated  albumin  due  to  the 
heating.  Details  regarding  the  composition  of  milk  and 
the  methods  for  its  examination  will  be  found  in  the  final 
chapter  of  this  volume. 

Cheese  is  a  most  valuable  food-stuff,  and,  as  a  milk 
product,  should  be  considered  at  this  time.  Good  cheese 
usually  contains  twice  as  much  nitrogen  and  three  times 
as  much  fat  as  the  same  weight  of  meat,  but  many  persons 
apparently  find  it  difficult  of  digestion  and  can  eat  but 
little  of  it.  This  is  perhaps  because  the  nutriment  is  so 
concentrated  and  because,  as  usually  eaten,  it  forms  a 
pasty,  solid  mass  in  the  stomach  into  which  the  gastric 
secretion  cannot  penetrate.  Mattieu  Williams  has  re- 
marked that  we  habitually  use  cheese  in  the  conditions  in 
which  it  is  most  indigestible — either  in  its  raw  state  or 
cooked  into  a  leathery  mass;  and  he  asserts  that  if  the 
cooking  is  such  that  it  is  thoroughly  mixed  with  other 
articles  of  food,  or  if  we  will  masticate  it  with  other  food, 
so  that  this  commingling  of  particles  takes  place,  it  will 
be  found  to  be  quite  digestible  by  almost  every  one.  He 
also  advises  the  addition  of  a  small  amount  of  potassium 
carbonate  in  the  cooking,  as  this  favors  the  solution  of  the 


FOOD.  207 

casein  and  replaces  that  salt  removed  in  the  whey.  It 
goes  without  saying  that,  as  a  food,  only  cheese  made  from 
whole  milk,  or  from  that  to  which  extra  cream  has  been 
added,  satisfies  all  requirements,  and  that  skim-milk 
cheeses  are  decidedly  less  nutritious  than  those  having  the 
full  proportion  of  fat. 

Butter,  consisting  as  it  does  largely  of  the  fat  of  milk, 
is  a  highly  nutritious  article  of  food  and  one  of  the  most 
digestible  of  its  class.  It  should  be  pure,  sweet,  and  free 
from  rancidity,  and  while  some  of  the  substitutes  offered 
in  its  stead  are  entirely  wholesome,  they  should  never  be 
sold  as  butter  or  used  to  adulterate  it.  Neither  should 
butter  contain  an  excess  of  water,  nor  of  casein,  as  its  food 
value  is  thereby  accordingly  lessened. 

Eggs  yield  almost  their  full  weight  of  food  in  a  concen- 
trated and  very  digestible  condition,  and  are  valuable  on 
this  account,  as  well  as  for  their  palatability  and  their 
value  in  the  preparation  of  many  dishes.  Containing 
practically  no  carbohydrates,  they  have  sufficient  food 
material  in  themselves  for  the  complete  development  of 
the  living  chick  with  the  aid  of  nothing  external  except 
the  oxygen  which  passes  through  the  shell :  the  lack  of 
the  carbohydrate  element,  one  of  the  essential  food  princi- 
ples ordinarily,  is  supplied  by  the  heat  from  the  mother 
hen  or  incubator,  which  is  sufficient  for  the  development 
and  maintenance  of  the  vital  processes,  since  the  un- 
hatched  creature  wastes  almost  no  energy  in  physical 
activity. 

The  white  of  egg  is  almost  pure  albumin  with  a  little 
water  and  some  salts;  the  yolk  contains  about  30  per  cent, 
of  fat  and  some  albumin.  The  albumin  coagulates  at 
about  170°  F.,  but  if  it  is  exposed  to  a  higher  temperature 
for  any  but  a  very  short  period  of  time,  it  becomes  hard 


208    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

and  difficult  of  digestion.  A  so-called  "  soft-boiled  "  egg 
is  scarcely  more  difficult  of  digestion  than  an  uncooked 
one,  and  is  certainly  more  palatable  to  almost  every  one. 

Eggs,  milk,  and  cheese  may  be  made  into  many  nutri- 
tious combinations  which  furnish  food  especially  agreeable 
to  the  sick,  as  well  as  to  those  whose  appetite  and  digestive 
functions  have  not  been  impaired. 

Good  meaty  when  deprived  of  its  contained  water,  is  a 
concentrated  food,  and  is  used  not  only  on  account  of  the 
large  amount  of  nutriment  it  contains,  but  for  its  rich  and 
agreeable  flavor.  It  represents  much  vegetable  matter 
converted  into  its  present  palatable  and  more  digestible 
form  by  the  metabolic  activity  of  the  animals  from  which 
it  came.  It  contains  all  the  essential  food  principles,  the 
carbohydrates,  however,  being  present  as  muscle  sugar  or 
iuosite  and,  as  in  milk,  in  very  small  proportion.  In  all 
fresh  meat  there  is  much  water,  but  more  in  lean  meat 
than  in  fat;  fat  bacon  contains  60  per  cent.;  lean  beef, 
from  75  to  78  per  cent,  of  water.  As  the  proportion  of 
fat  increases  the  quantity  .of  albuminoids  or  proteids 
decreases :  thus,  lean  beef  may  have  only  2  per  cent,  of 
fat  to  from  20  to  24  per  cent,  of  proteids;  while  bacon 
has  about  24  per  cent,  of  fat  to  15  per  cent,  of  proteids. 

Of  the  varieties  of  meat  commonly  used,  beef  is  the 
most  nutritious.  Good  beef  should  not  be  too  pale  nor  too 
dark,  should  show  no  blood  clots,  have  almost  no  odor,  be 
elastic  and  not  soggy  to  the  touch,  be  well  marbled  with 
clean,  white  fat,  and  have  compact  flesh.  Dark  beef  indi- 
cates that  the  animal  was  not  properly  bled,  or  has  had  some 
febrile  disease;  wet  and  flabby  meat,  that  it  is  approach- 
ing decomposition.  The  flesh  of  young  animals  is  more 
tender  than  that  of  older  ones,  but  not  as  digestible,  partly 
because  the  young  flesh  cannot  be  so  thoroughly  masticated 


FOOD.  209 

and  the  fibres  so  well  separated.  Therefore,  veal  is  not  as 
digestible  as  beef,  nor  lamb  as  mutton.  "  Young  flesh  is 
less  stimulating  and  nutritious  and  more  gelatinous  than 
that  of  the  adult. "  (Vaughan.)  Veal  should  not  be  too 
pale,  as  that  indicates  ante- mortem  bleeding  or  too  young 
an  animal.  The  calf  should  be  at  least  one  month  old 
before  the  killing. 

Mutton  is  more  digestible  than  beef,  but  not  so  nutri- 
tious. Its  flavor  is  objectionable  to  some.  Pork  is  an 
economical  food  for  the  poor  man,  as  good  pigs  store  up 
three  times  as  much  of  the  food  they  eat  as  does  the  ox. 
The  flesh  is  also  easily  preserved  by  drying  or  smoking, 
and  ham  and  bacon  are  exceptions  to  the  rule  that  dried 
meats  are  more  indigestible  than  fresh  ones.  Again,  pork 
fat  furnishes  much  heat  for  cold  weather  by  its  oxidation 
and  combustion  in  the  body.  But  it  must  be  remembered 
that  it  requires  good  digestive  apparatus  to  dispose  of  it, 
and  that  much  pork  is  not  to  be  advised  for  those  of 
sedentary  habits. 

The  flesh  of  poultry  is  acceptable  to  most  palates,  if  not 
too  old  and  tough.  White  meat  is  more  digestible  than 
the  dark,  but  not  so  nutritious  or  rich  in  flavor,  since  the 
latter  is  more  highly  nitrogenous.  Chicken  broth  is  more 
nutritious  and  more  laxative  than  that  made  from  mutton. 

Fish  is  not  sufficiently  stimulating  to  constitute  the 
chief  flesh  diet  of  a  people,  but  it  furnishes  variety,  and 
undoubtedly  should  be  used  largely  by  those  subject  to 
neurosal  affections,  on  account  of  its  contained  phospho- 
rus. White- meated  fish  are  more  delicate  in  flavor  and 
more  easily  digested,  but  not  so  stimulating  as  those  of 
red  flesh.  Some  fish  are  poisonous,  either  by  nature  or 
from  inhabiting  foul  waters;  while  any  fish  may  become 
so  if  undergoing  decomposition.  Shell-fish  are  particu- 

14 


210    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

larly  liable  to  develop  poisonous  ptomaines  in  the  process 
of  decomposition,  and,  consequently,  only  such  as  are 
absolutely  fresh  should  be  used.  Oysters  and  clams  which 
have  been  taken  from  a  water  contaminated  by  sewage 
may  also  convey  the  germs  of  infectious  diseases,  such  as 
typhoid  fever;  an  instance  of  this  having  been  proven  in 
the  case  of  a  recent  epidemic  of  the  latter  disease  in  Con- 
necticut, which  was  investigated  and  reported  by  Prof. 
Conn,  of  Wesleyan  University. 

"  The  following  meats  should  not  be  eaten:  1.  The 
flesh  of  all  animals  dead  of  internal  diseases,  or  which 
have  been  killed  while  suffering  from  such  diseases,  or 
animals  killed  by  overdriving.  2.  The  flesh  of  animals 
with  contagious  diseases  that  may  be  transmitted  to  man. 
3.  The  flesh  of  animals  that  have  been  poisoned.  4.  The 
flesh  of  animals  with  severe  infectious  diseases,  as  pyaemia, 
etc.  5.  Flesh  that  contains  parasites  that  may  be  trans- 
mitted to  man.  6.  All  putrid  flesh.'7  (Gerlach.) 

Competent  inspectors  should  be  and  are  appointed  by 
Government  and  State  authorities  to  examine  the  various 
meats  offered  for  sale  in  the  large  cities,  and  undoubtedly 
do  much  good  in  preventing  the  sale  of  meat  that  is  unfit 
for  use.  Unfortunately,  from  false  ideas  of  economy, 
they  are  too  few  in  number  in  many  communities  to  be 
able  to  attend  to  all  the  work  that  is  required  of  them. 

Coplin  and  Bevan  give  the  following  as  diseases  which 
are  to  be  specially  guarded  against,  and  also  discuss  the 
symptoms  of  these  maladies  and  the  appearances  they  pro- 
duce in  the  flesh  and  viscera  of  animals  killed  while  suffer- 
ing from  them:  In  cattle,  epidemic  pleuro-pneumonia, 
foot-  and  mouth-disease,  contagious  typhus,  anthrax, 
tuberculosis,  actinomycosis,  Texas  fever,  dropsical  affec- 
tions, and  indigestion.  In  sheep,  braxy,  variola  ovina, 


FOOD.  211 

black  quarter,  phthisis,  fluke  disease,  and  gid.  In 
swine,  anthrax,  hog  cholera,  measles,  and  trichiniasis.1 
It  should  also  be  remembered  that  the  intestinal  para- 
sites, such  as  tape- worms  and  round  worms,  often,  if  not 
usually,  gain  entrance  into  the  system  through  the  inges- 
tion  of  meat  containing  them  in  their  embryonal  or  larval 


Therefore,  in  cooking  meat,  every  part  should  be  heated 
to  at  least  160°  F.  to  destroy  any  disease  germs  or  para- 
sites it  may  contain,  as  very  rare  meat  may  still  contain 
these  organisms  in  a  living  state.  Tuberculosis,  for 
instance,  may  be  incurred  by  eating  flesh  imperfectly 
cooked,  since  its  germs  are  hard  to  kill;  though  it  must 
be  said  that  this  disease  is  not  so  likely  to  affect  the  mus- 
cular tissues  of  an  animal  as  others  of  the  maladies  men- 
tioned. The  development  of  ptomaines  in  flesh  may  also 
make  it  very  poisonous,  and  this  is  especially  likely  to 
occur  in  meats  that  have  been  kept  a  long  time  after  kill- 
ing or  in  those  preserved  in  cans  or  other  packages  that 
have  been  imperfectly  heated  or  sealed. 

Meat  is  cooked  to  improve  it  in  appearance  and  to  make 
it  more  agreeable  to  the  palate  and  digestion.  The  effect 
of  cooking  upon  muscle  tissue  is  "  to  loosen  the  bundles 
of  fibrillse  from  each  other  so  that  they  are  readily  torn 
asunder  or  crushed  by  the  teeth/7  Perfectly  cooked  flesh 
is  more  savory  than  when  it  is  either  underdone  or  over- 
done. Foster  says  that  in  the  stomach  "the  natural 
bundles  of  meat  and  vegetables  fall  asunder,  the  muscular 
fibres  split  up  into  disks,  and  the  protoplasm  is  dissolved 
from  vegetable  cells.7'  However,  "if  the  meat  be  not 
chewed  properly  but  l  bolted/  the  solvent  gastric  juice  can 

1  Manual  of  Practical  Hygiene,  1st  edition,  p.  132,  et  seq. 


212    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

only  act  on  the  exterior  of  the  mass;  while  '  lumps '  offend 
the  stomach  and  arrest  the  gastric  secretion.'7 

Meat  cooked  before  rigor  mortis  sets  in  may  be  tender; 
cooked  during  the  rigor,  it  is  tough,  and  is  masticated  with 
difficulty;  after  the  rigor  is  past  the  meat  becomes  tender 
again  when  cooked,  provided  it  was  so  originally. 

In  cooking  meat,  the  ultimate  condition  in  which  we 
wish  it  to  be  should  always  be  kept  in  mind,  and  pains 
should  also  be  taken  not  to  overcook  or  use  too  high  a 
temperature.  The  processes  pursued  in  making  a  good 
soup  or  broth,  and  in  cooking  so  that  it  may  retain  all  its 
juices,  salts  and  flavors,  are  radically  different.  In  the 
first  case,  it  is  desired  to  extract  as  much  of  soluble  con- 
stituent of  the  flesh  as  possible,  and  to  do  this  the  meat 
should  be  cut  into  small  pieces  and  allowed  to  remain  for 
a  time  in  cold  water,  this  afterward  being  very  gradually 
raised  to  a  temperature  of  about  160°  F.  In  this  way  the 
juices  exude  and  the  salts  and  soluble  parts  of  the  meat 
are  dissolved  before  the  pores  are  closed  by  the  coagula- 
tion of  the  albumin. 

On  the  other  hand,  if  it  is  desired  to  retain  the  juices 
and  savor  in  the  meat,  the  piece  should  be  large  as  pos- 
sible, that  the  surface  exposed  will  be  small  in  proportion 
to  the  volume.  The  piece  is  then  to  be  first  subjected  to 
a  temperature  as  high  as  possible,  that  the  surface  may  be 
cooked  at  once  and  the  albumin  coagulated,  the  juices 
being  thus  prevented  from  escaping  by  the  sealing  of  the 
pores.  In  boiling  this  end  is  attained  by  plunging  the 
meat  at  once  into  boiling  water;  in  roasting,  by  having 
the  fire  or  oven  very  hot.  After  this  first  heating  it  is 
best  to  diminish  the  degree  of  heat  somewhat,  that  the 
subsequent  cooking  of  the  interior  may  go  on  more  slowly 
and  the  temperature  within  may  not  rise  above  the_coagu- 


FOOD.  213 

lating  point  to  make  the  fibres  hard  and  stringy.  Meat 
cooked  in  this  way  should  be  tender,  juicy,  and  full  of 
flavor.  Broiling  or  grilling  is,  of  course,  but  a  modified 
roasting. 

Soups  and  broths  made  of  meat  juices  alone  and  without 
the  addition  of  other  substances  are  stimulating  rather  than 
nutritious,  as  they  contain  little  albumin,  carbohydrates, 
or  fat.  However,  if  certain  vegetables  be  added  to  the 
soup,  the  latter  will  gain  sufficient  of  these  food-principles 
and  be  highly  nutritious,  and  such  vegetable  soups  are  of 
great  value  in  all  schemes  of  economic  cooking.  Bones 
are  also  of  value  on  account  of  the  salts,  gelatine,  and 
other  soluble  organic  matter  which  they  contain,  and 
with  vegetables  they  make  especially  nutritious  and  easily 
digested  soups. 

The  meat  from  which  soup  is  made,  on  the  other  hand, 
is  not  all  that  is  desirable,  for  though  it  still  contains  albu- 
min and  fat,  it  has  lost  its  salts  and  savoriness,  and 
is  unpalatable  and,  therefore,  not  easily  digested.  It 
needs  something — a  sauce  or  condiment,  or  preferably,  a 
meat  extract,  for  meat  extracts  are  nothing  but  thin  soups 
evaporated  to  dry  ness  or  condensed.  Or,  if  both  soup  and 
the  meat  be  taken  at  the  same  meal,  the  things  lacking  in 
each  are  supplied  in  the  other,  and  the  needs  of  digestion 
and  nutrition  are  supplied. 

Frying  meat,  as  is  commonly  practised,  should  not  be 
condoned  or  tolerated,  as  it  renders  the  albumin  of  the 
flesh  extremely  tough,  beside  soaking  it  with  fat  or  grease, 
and  thus  greatly  increasing  the  difficulty  of  its  digestion. 
But  frying  by  total  immersion  in  boiling  fat  is  an  excellent 
way  of  cooking  meats  containing  much  water,  and  espe- 
cially fish,  for  the  boiling  point  of  fat  or  oil  is  very  high, 
and  the  meat  is  instantly  cooked  on  the  outside,  while  the 


214    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

water  in  the  interior,  being  converted  into  steam,  prevents 
the  ingress  of  fat  by  its  expansion,  cooks  the  albumin,  and 
leaves  the  flesh  in  a  light,  flaky  condition.  But  the  fat 
must  be  boiling  hot  when  the  meat  is  immersed,  and  the 
latter  must  not  be  allowed  to  remain  in  the  former  longer 
than  just  suffices  for  the  perfect  cooking. 

Beef-tea,  as  ordinarily  made,  is  only  a  thin  extract  of 
beef,  the  stimulating  properties  of  which  will  be  consid- 
ered hereafter.  To  make  a  -beef-tea  containing  any  con- 
siderable amount  of  nutriment,  the  meat  from  which  the 
juices  have  been  extracted  should  be  dried,  pounded  fine, 
and  all  fibrous  and  tendinous  portions  should  be  removed. 
This  pounded  beef  should  then  be  added  to  the  liquid 
extract,  which  then  only  is  really  a  food.  However,  the 
mixture  should  always  be  seasoned,  even  for  the  sick,  that 
it  may  be  thoroughly  acceptable  to  both  palate  and  stomach. 
In  making  the  extract,  remember  that  the  meat  should  be 
cut  into  very  small  pieces  and  added  to  cold  water  in  about 
the  proportion  of  one  pound  of  lean  meat  to  one  pint  of 
water,  and  that  the  whole  should  be  brought  to  the  boiling- 
point  very  slowly. 

The  cereals  form  one  of  the  most  valuable  kinds  of 
foods.  All  but  rice  contain  considerable  proteid  matter — 
from  10  to  20  per  cent. — beside  carbohydrates  which  pre- 
dominate, some  fat,  and  a  goodly  proportion  of  phosphates. 
Rice  has  only  5  per  cent,  of  proteids  to  75  per  cent,  of 
starch,  but  it  is  easily  digested,  and  is,  therefore,  a  valu- 
able food  for  the  young  and  the  sick;  it  is  also  well  fitted 
for  a  chief  food  for  dwellers  in  hot  climates  on  account  of 
its  low  heat  production. 

Wheat  is  the  most  nutritious  cereal,  and  bread  made 
from  it  is  aptly  called  "  the  staff  of  life,"  since  it  is  a 
food  which,  with  the  addition  of  a  little  extra  fat  and 


FOOD.  215 

albumin,  furnishes  the  essentials  in  proper  proportion  for 
the  support  of  life.  Barley  closely  resembles  wheat  in 
composition,  and  rye  also  is  rich  in  nutriment,  though 
perhaps  a  little  more  difficult  of  digestion  than  wheat. 
Oats  are  valuable  on  account  of  the  large  amount  of  fat 
they  contain — over  5  per  cent. — beside  a  full  share  of 
proteids,  starch,  and  salt.  Corn  or  maize,  though  not  a 
true  cereal,  furnishes  a  valuable  food  with  considerable 
fat;  it  also  contains  a  vegetable  fibrin.  The  proteid  con- 
stituents of  the  cereals  are  vegetable  albumin,  casein,  and 
gluten,  the  last  of  these  being  most  abundant  in  wheat 
and,  perhaps,  of  the  highest  food  value. 

Grinding  breaks  up  the  grain  and  the  starch  granules  of 
the  cereals,  aids  in  separating  indigestible  parts,  and  renders 
the  starch  much  more  suitable  for  cooking.  Wheat  flour 
ground  by  the  old  method  should  be  soft  and  smooth,  but 
that  made  by  the  new  roller-process  is  more  apt  to  be 
slightly  granular.  It  should  not  be  too  white,  as  that 
indicates  a  lack  of  the  proper  proportion  of  gluten,  and 
should  contain  everything  but  the  outer  husk  of  the  grain. 
The  inner  coats  should  be  retained  in  the  flour,  as  they 
hold  a  good  part  of  the  gluten  and  practically  all  of  the 
grain  salts.  Corn-meal  should  be  dry  and  powdery,  or, 
at  least,  not  too  granular.  Flour  of  any  kind  should  be 
kept  well  covered  in  a  dry  place,  and  should  contain  no 
living  organisms  nor  any  adulterants. 

Bread  is  practically  made  of  flour,  water,  and  salt; 
though  sugar,  milk,  etc.,  may  be  added  to  improve  the 
flavor.  As  flour  and  water  alone  make  a  tough  and 
indigestible  mass,  bread  is  leavened  to  make  it  easier  of 
mastication  and  digestion,  and  for  this  purpose  either 
yeast,  baking  powder,  or  aeration  is  employed.  Yeast  at 
the  proper  temperature  rapidly  converts  the  starch  or 


216    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

sugar  into  carbonic-acid  gas  and  alcohol,  the  former  of 
which  in  escaping  makes  the  dough  porous  and  light,  the 
walls  of  the  cavities  it  produces  being  kept  from  collapsing 
by  the  tenacity  of  the  gluten  until  the  heat  has  fixed  them 
permanently.  As  the  heat  of  baking  dissipates  both  the 
gas  and  alcohol,  from  10  to  12  per  cent,  of  the  weight  of 
the  flour  used  is  lost  by  this  method.  Moreover,  if  the 
fermentation  goes  beyond  a  certain  point,  lactic  and  acetic 
acids  are  formed,  and  the  bread  becomes  "  sour/7  Con- 
sequently, it  has  been  advised  that  the  yeast  method  be 
discarded  and  that  the  leavening  be  done  by  means  of 
baking-powders  or  aeration.  Carbonic-acid  gas  is  evolved 
from  the  baking-powders  upon  the  application  of  heat  and 
moisture,  and  the  bread  is  made  light  by  the  gas,  with  no 
loss  of  food  substance,  and,  if  the  powders  are  pure,  with 
nothing  harmful  being  added  to  the  bread.  There  should 
be  no  alum  or  other  adulterants  in  the  baking-powders, 
any  more  than  in  the  bread  itself.  Alum  unites  with  the 
phosphates  of  the  flour,  rendering  them  insoluble  and  pre- 
venting their  absorption  from  the  alimentary  tract.  Bread 
may  also  be  leavened  on  a  large  scale  by  forcing  air  or 
carbonic-acid  gas  under  high  pressure  into  the  dough,  or 
by  mixing  the  flour  with  water  heavily  charged  with  the 
latter  gas.  In  this  method,  also,  there  can  be  no  loss  of 
food  material  nor  any  detriment  to  the  bread,  provided 
cleanly  precautions  are  observed. 

Good  wheat  bread  should  be  almost  white,  light,  sweet, 
spongy,  and  with  a  crust  easily  broken  and  equal  in  bulk 
to  about  one-quarter  of  the  loaf.  As  considerable  of  the 
starch  has  been  converted  into  dextrine  in  the  crust,  the 
latter  is  more  easily  digested  than  the  interior  of  the  loaf. 
Fresh  bread  is  not  nearly  so  digestible  as  that  which  is  a 
day  or  two  old.  As  stated,  bread  needs  only  a  little  added 


FOOD.  217 

fat  and  albumin  to  make  it  a  perfect  food,  and  this  it  gets 
almost  if  not  quite  sufficiently  in  the  butter  which  we 
commonly  use  upon  it. 

The  vegetables  in  common  use  are  valuable  articles  of 
food,  in  that  they  give  us  the  larger  portion  of  our  carbo- 
hydrates and  also  furnish  an  agreeable  variety  from  day 
to  day.  In  the  fresh  state  they  contain  considerable  water 
— from  75  to  90  or  95  per  cent.,  the  residue  being  mainly 
one  or  the  other  of  the  carbohydrates.  Potatoes  exemplify 
this  well,  since  they  contain  but  little  proteids  and  fat, 
and  practically  all  of  their  solid  matter  is  starch.  On 
account  of  their  customary  cheapness  and  ease  of  growth 
and  storage  they  are  usually  considered  to  be  a  good  article 
of  food  for  the  poor  man,  but  it  should  not  be  forgotten 
that  other  foods  which  are  apparently  more  expensive  may 
actually  at  times  be  cheaper  than  potatoes,  both  on  account 
of  containing  those  principles  which  the  latter  lack  and 
because  they  may  require  less  expenditure  of  digestive 
energy.  Beets  contain  much  sugar  and  are  nutritious, 
palatable,  and  easily  digested.  Cabbage,  cress,  spinach, 
and  other  greens,  are  especially  valuable  for  the  organic 
salts  which  they  contain,  and  because  they  serve  so  well 
as  relishes.  Celery  and  lettuce  are  nerve  sedatives,  and 
asparagus  acts  as  a  diuretic  and  is  thought  to  be  of  special 
benefit  to  the  kidneys. 

The  seeds  of  the  leguminous  group  of  plants,  such  as 
peas,  beans,  lentils,  etc.,  contain  from  22  to  25  per  cent,  of 
proteid  matter  in  the  form  of  vegetable  casein,  and  almost 
50  per  cent,  of  starch.  It  is  on  account  of  this  abundance 
of  food-matter  that  they  make  such  a  valuable  addition 
to  soups  and  the  like,  and  for  the  same  reason  they  should 
also  be  considered  and  used  in  any  dietary  where  economy 
of  expense  is  to  be  a  factor.  Green  peas  and  beans  are 


218    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

much  more  digestible  than  those  that  have  ripened  and 
dried,  though,  of  course,  they  do  not  yield  as  much  food, 
weight  for  weight,  as  the  latter. 

All  vegetables  should  be  cooked  so  as  to  retain  their 
salts,  or  else  the  water  in  which  they  are  cooked  and 
which  contains  these  salts  should  be  used  in  making  soup 
or  broth,  to  be  served  at  the  same  meal  with  the  vege- 
tables. This  is  especially  advisable  with  regard  to  pota- 
toes and  sweet  potatoes,  as  their  soluble  salts  have  much 
to  do  with  their  digestibility.  It  is  for  this  reason  that  a 
properly  roasted  potato  is  always  better  than  a  boiled  one, 
and  that  steamed  vegetables  are  both  more  palatable  and 
more  digestible  than  those  which  have  been  cooked  under 
water.  In  fact,  Mattieu  Williams  has  even  suggested  that 
possibly  one  reason  why  gout  is  so  prevalent  among  Eng- 
lishmen is  because  they  habitually  eat  boiled  vegetables 
and  throw  away  the  water  in  which  these  have  been  cooked. 
The  salts  not  only  help  in  the  digestion  of  the  starches, 
but  they  furnish  bases  to  unite  with  and  render  soluble 
the  irritating  acids  that  produce  the  gouty  symptoms.  It 
should  also  be  remembered  that  the  dried  legumes  should 
always  be  softened  by  soaking  before  cooking,  and  that 
they  as  well  as  other  vegetables  should  be  cooked,  when- 
ever possible,  in  soft  water. 

Fruits  are  especially  valuable  on  account  of  their  flavor, 
acceptability  to  the  palate,  benefit  to  the  digestion,  and  for 
their  laxative  action.  Ripe  fruits  may  be  eaten  freely,  but 
in  most  cases,  preferably  early  in  the  day.  Eresh  fruits 
are  usually  better  than  those  dried  or  otherwise  preserved ; 
but  where  the  former  cannot  be  had,  the  latter  should  be 
used  freely,  and  all  should  be  used  whenever  possible 
throughout  the  year.  Green  fruit,  or  that  which  has  begun 
to  decay,  should  not  be  eaten,  for  obvious  reasons. 


FOOD. 


219 


Nuts  are  nutritious  on  account  of  the  high  percentage 
of  fat  that  most  of  them  contain,  but  are  difficult  of  diges- 
tion unless  carefully  masticated.  Recently  pastes  made 
from  various  nuts  have  been  placed  on  the  market,  and 
are  to  be  considered  as  an  agreeable  addition  to  our  die- 
taries. Prepared  starches,  such  as  arrow-root,  tapioca, 
sago,  etc.,  are  very  digestible  and,  therefore,  useful,  espe- 
cially in  the  preparation  of  food  for  the  young  or  the  sick. 

The  following  diagram  may  be  of  service  to  some  in 
determining  the  value  of  certain  food-stuffs. 


PIG.  34. 


RELATIVE  VALUE  OF  STAPLE  FOODS. 


HEAT  A   ENERGY  WATER          FLESH  A  BONE  f 

C".' ' ..". '"~)  c        )  in 


CHAPTEE    VII. 

STIMULANTS   AND   BEVERAGES. 

THE  essential  function  and  property  of  stimulants  is 
to  liberate  some  of  the  latent  force  of  the  body,  and  they 
are  of  use  and  value  in  sudden  emergencies,  to  tide  the 
system  over  important  crises,  to  hasten  a  tardy  convales- 
cence, or,  perchance,  to  whip  up  a  flagging  digestion  so 
that  it  may  the  better  prepare  food  for  the  repair  of  waste 
or  the  supplying  of  body  fuel.  Those  stimulants,  exclud- 
ing drugs,  with  which  we  are  most  concerned  are  of  three 
classes,  viz.,  nitrogenized  vegetable  stimulants,  such  as  tea 
and  coffee;  nitrogenized  animal  stimulants,  as  beef-tea  and 
meat-extracts;  and  alcohol.  All  these  are  "  force-libera- 
tors," though  alcohol  may  sometimes  act  the  part,  in  more 
moderate  measure,  of  a  "force-producer,"  and  it  is  well 
to  remember  that  they  scarcely  give  anything  at  all  to 
renew  or  replace  the  energy  which  they  set  free. 

This  being  so,  care  should  always  be  taken  that  some 
food  may  be  supplied  during  or  shortly  after  the  stimula- 
tion produced  by  the  agents  in  question,  in  order  that  the 
body  may  have  a  new  store  of  force  to  replace  that  which 
has  been  liberated.  Especially  is  this  necessary  in  cases  of 
sickness,  and  as  the  soluble  carbohydrates  furnish  fuel  and 
consequent  heat  and  energy  to  carry  on  the  vital  pro- 
cesses, these  even  more  than  other  kinds  of  food  are  to  be 
supplied  and  will  generally  be  well  received  and  utilized 
by  patients  or  others  in  need  of  stimulation;  and,  just  as 
we  must  not  depend  on  stimulants  alone  to  the  exclusion 


STIMULANTS  AND  BEVERAGES.  221 

of  food,  so  also  must  we  take  care  not  to  continue  their 
use  any  longer  than  is  necessary  to  attain  our  object,  and 
likewise  must  not  over-stimulate  or  carry  the  action  so  far 
that  the  body  is  left  poor  and  weaker  in  force  than  before 
the  use  of  the  stimulants  began. 

For  example,  beef-tea  constantly  stimulates  the  vital 
and  nervous  functions  to  greater  activity,  this  requiring 
that  either  tissue  or  food  be  oxidized  to  produce  the  neces- 
sary energy.  But  beef -tea,  as  ordinarily  made,  gives  no 
food  in  itself,  and,  unless  this  be  otherwise  supplied,  the 
body  tissue  must  be  consumed  and  the  result  must  be  in 
the  end  disastrous;  and  yet  this  is  what  occurs  to  many 
patients  through  the  mistaken  idea  that  beef -tea  is  both 
nourishing  and  stimulating.  When  "  whole  beef-tea " 
(the  recipe  for  which  has  already  been  given)  is  used  these 
remarks  do  not  apply,  since  it  contains  some  true  food, 
though  even  here  soluble  carbohydrates  may  be  wisely 
added. 

The  stimulating  factors  in  ordinary  beef -tea  are  the 
extractives,  such  as  kreatin  and  kreatinine,  which  are  pro- 
ducts of  the  wear  and  tear  of  life,  intermediate  between 
living,  active  tissue  and  the  final  excretory  matters,  such 
as  urea  and  uric  acid;  hence,  they  can  have  little,  if  any, 
real  food  value.  Beside  these  the  beef-tea  contains  only 
the  salts  of  the  meat,  which,  though  valuable,  are  not  force 
producers. 

The  active  principles  of  the  nitrogenized  vegetable  stim- 
ulants resemble  very  closely  in  chemical  composition  not 
only  the  meat  extractives,  but  also  those  drugs,  like 
strychnine,  which  are  used  in  medicine  as  tonics  and  cere- 
bro-spinal  stimulants,  and  they  act  physiologically  in  a 
similar  though  milder  manner. 

As  beverages  tea,  coffee,  and  cocoa  supply  fluid  for  the 


222    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

system  and  that  stimulation  of  the  assimilative  functions 
that  gives  the  sense  of  comfort  after  their  use;  cocoa  and 
chocolate  having  also  the  advantage  of  supplying  some 
food.  But  these  beverages  can  all  be  abused  in  their  use 
as  readily  as  can  beef-tea  or  alcohol,  and  "  tea-  or  coffee- 
drunkards"  are  not  uncommon  in  our  hospitals  or  in 
private  life.  The  teacup  is  not  always  the  one  that 
"  cheers  but  does  not  inebriate."  Women  especially  who 
drink  much  tea  are  apt  to  be  nervous  and  dypseptic,  to 
have  the  "  tea-drinker7 s  heart,"  and  to  suffer  from  head- 
aches and  neuralgias.  They  depend  upon  tea  to  take  the 
place  of  food,  and  soon  use  up  what  little  store  of  force 
they  may  have  had,  since  they  fail  to  replenish  it  with 
new  fuel-food. 

Men  are  more  addicted  to  the  use  and  abuse  of  »coffee, 
and  often  manifest  symptoms  directly  traceable  to  it. 
While  caffeine  increases  heart  action,  and  may  be  used  to 
advantage  in  cases  of  cardiac  debility,  for  the  same  reason 
it  should  be  taken  with  caution  and  in  moderation  where 
the  cardiac  action  is  already  too  vigorous.  Vogel  has 
advised  the  use  of  strong  coffee  with  cream  as  a  tonic  and 
food  in  debility  accompanying  the  acute  diseases  of  chil- 
dren. 

It  is  interesting  to  note  that  among  all  nervous,  ener- 
getic people  the  use  of  some  one  or  the  other  of  these 
stimulant  beverages  is  common,  and  that  "  total  abstain- 
ers" from  alcohol  seem  instinctively  to  take  to  tea  or 
coffee.  And  while  it  is  probably  theoretically  true  that 
the  healthy  person  would  better  abstain  entirely  from  the 
use  of  stimulants,  except  in  emergencies  or  at  rare  inter- 
vals, yet  this  almost  universal  demand  and  use  of  them 
probably  indicates  that  under  our  present  high  tension  of 
living  there  is  a  practical  physiological  demand  and  need 


STIMULANTS  AND  BEVERAGES.  223 

for  them  that  perhaps  had  better  be  satisfied  in  a  measure, 
but  with  moderation  and  judgment. 

Alcohol  Liebig  says  "  alcohol  stands  only  second  to 
fat  as  a  respiratory  material/7  but  adds  that  "  the  same 
effect  could  be  produced  in  the  body  by  means  of  saccha- 
rine and  farinaceous  articles  of  food  at  one-fourth  or  one- 
fifth  the  cost."  Fothergill  also  holds  "that  the  chief 
portion  of  the  alcohol  ingested  undergoes  consumption  in 
the  body/7  but  insists  that  "  the  question  of  '  alcohol  as 
a  food J  can  never  be  separated  or  divorced  from  that  of 
'  alcohol  as  a  stimulant'  or  as  a  force-liberator."  Again, 
Liebig  writes,  that  "  the  use  of  spirits  is  not  the  cause  but 
the  effect  of  poverty.  It  is  the  exception  to  the  rule  when 
the  well-fed  man  becomes  a  spirit-drinker.  On  the  other 
hand,  when  the  laborer  earns  by  his  work  less  than  is 
required  to  provide  the  amount  of  food  which  is  indispen- 
sable in  order  to  restore  fully  his  working  power,  an 
unyielding,  inexorable  law  or  necessity  compels  him  to 
have  recourse  to  spirits.  He  must  work;  but  in  conse- 
quence of  insufficient  food,  a  certain  portion  of  his  work- 
ing power  is  daily  wasting.  Spirits,  by  their  action  on 
the  nerves,  enable  him  to  make  up  the  deficient  power  at 
the  expense  of  his  body;  to  consume  to-day  that  quantity 
which  naturally  ought  to  have  been  employed  a  day 
later."  This  may  also  be  the  case  where  there  is  an 
abundance  of  food,  but  where  it  is  improperly  chosen  for 
the  needs  of  the  individual  or  ruined  in  the  preparation 
by  bad  cooking.  Education  in  the  principles  of  the 
scientific  and  economical  selection  of  food  and  its  prepara- 
tion may  thus  become  a  means  of  preventing  those  diseases 
that  depend  on  or  are  aggravated  by  insufficient  or  im- 
proper food,  and  consequent  alcoholic  excesses.  The  effect 
of  alcohol  upon  the  weak  and  savage  races  is  much  more 


224    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

marked  and  disastrous  than  upon  the  civilized  and  strong; 
so  it  harms  the  health  of  the  underfed  and  overworked 
much  more  than  it  does  that  of  the  well-fed  man  of 
means  and  leisure,  and  women  and  children  more  than 
adult  men.  This  latter  point  is  to  be  remembered  in 
practice. 

Remember  also  that,  while  alcohol  is  partially  a  respir- 
atory stimulant,  it  is  a  force-liberator  and  consumes  the 
body  store,  and  unless  given  with  other  readily  oxidizable 
food  the  risk  is  run  of  putting  a  patient  "  in  a  grave  never 
dug  by  Nature/'  especially  where  there  is  already  danger 
of  the  patient  sinking  from  exhaustion.  But  it  is  just  in 
these  cases,  when  given  with  other  food,  that  we  find  alco- 
hol a  most  valuable  therapeutic  agent.  Give  it  with  foods 
that  produce  heat  and  force — i.  e.,  some  form  of  the  solu- 
ble carbohydrates,  as  maltose,  malt  extracts,  milk,  milk- 
whey,  or  even  sugar.  "Where  the  assimilative  powers  are 
weak  it  may  be  advantageous  or  necessary  to  partially  or 
wholly  predigest  these  foods;  but  above  all,  remember  to 
replace  what  alcohol  takes  from  the  body,  or  physiological 
bankruptcy  will  ensue.  Note  also  that,  though  alcohol 
may  be  in  one  sense  a  food,  it  is  a  very  costly  one,  and 
that  intoxication  must  occur  long  before  a  man  could  get 
the  equivalent  of  a  full  meal. 

Alcohol  is  to  be  used  in  sickness  practically  to  sustain 
the  vital  powers,  to  meet  emergencies,  and  to  lift  the 
patient  over  obstructions  in  the  road  to  health;  and  such 
use  requires  a  thorough  knowledge  of  its  action  coupled 
with  the  highest  judgment. 

In  malt  liquors  there  is  considerable  maltose  left  un- 
changed, thus  combining  with  the  alcohol  a  soluble  carbo- 
hydrate of  the  highest  value,  and  these  brewed  ales,  etc., 
may  often  be  used  with  benefit  as  tonics,  especially  where 


STIMULANTS  AND  BEVERAGES.  225 

convalescence  is  prolonged.  The  stronger  distilled  liquors 
are  diffusible  cardiac  stimulants,  and  are  especially  valu- 
able in  emergencies,  but  the  continued  use  of  them  must 
only  be  advised  with  great  caution.  Fothergill  gives  two 
excellent  rules  for  the  use  of  alcohol  by  the  healthy  : 
"  First,  never  have  alcohol  in  the  brain  when  it  has  work 
to  do;  second,  a  little  alcohol  betwixt  a  man  and  past 
trouble  is  permissible;  but  it  is  not  well  to  put  a  little 
alcohol  in  front  of  a  coming  trouble. "  Murchison,  in 
his  work  on  Fevers,  lays  down  these  rules  for  practice, 
which  it  would  be  well  for  all  to  adopt :  u  What  are  the 
conditions  of  the  animal  economy  in  which  alcohol  may 
be  of  positive  use?  That  there  are  such  conditions,  I 
believe  cannot  be  denied  by  any  one  who  has  honestly 
studied  the  subject;  but  they  are  not  the  conditions  of  per- 
fect health.  It  is  especially  when  the  circulation  is  weak 
or  sluggish  that  a  daily  allowance  of  alcohol  may  do  good. 
Thus  :  1.  Alcohol  is  useful  in  the  course  of  most  acute 
diseases,  when  the  organs  of  circulation  begin  to  fail,  as 
they  are  apt  to  do.  A  moderate  quantity  usually  suffices. 
The  large  quantity  still  sometimes  administered  may  do 
harm  by  inducing  congestion  of  internal  organs.  2.  In 
convalescence  from  acute  diseases,  or  from  weakening 
ailments,  when  the  circulation  remains  feeble  and  the  tem- 
perature is  often  subnormal,  alcohol  is  useful  in  promoting 
the  circulation  and  assisting  the  digestion.  3.  In  persons 
of  advanced  life  the  circulation  is  also  often  feeble,  and  a 
moderate  allowance  of  alcohol  often  appears  to  be  bene- 
ficial. All  other  conditions  of  the  system  marked  by 
weakness  of  the  muscular  wall  of  the  heart,  whether  per- 
manent or  transient,  are  usually  benefited  by  alcohol." 
vAlcohol  is  a  good  servant,  but  a  bad  master.  King  Cham- 
bers says  :  "  Let  alcohol  be  taken  never  as  a  stimulant  or 

15 


226    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

preparative  for  work,  but  as  a  defence  against  injury 
done  by  work,  whether  of  mind  or  body.  For  example, 
it  is  best  taken  with  the  evening  meal  or  after  toil.  Let 
the  increase  in  the  desire  for  and  the  power  of  digesting 
food  be  the  guide  and  limit  to  the  consumption  of  all 
alcoholic  liquids.  Let  the  forms  be  such  as  contain  the 
least  proportion  of  fusel  oil.  Let  all  with  an  hereditary 
tendency  to  hysteria  or  other  functional  diseases  of  the 
nervous  system  refrain  from  its  use  altogether,  even 
though  as  yet  in  good  health." 

Beverages. 

To  comment  individually  upon  the  multitude  of  non- 
alcoholic and  non-stimulating  beverages  that  are  now  more 
or  less  generally  used,  is  both  impracticable  and  unneces- 
sary, nor  will  an  attempt  to  classify  them  be  of  much  value. 
For  the  most  part  they  serve  only  to  please  the  palate; 
though  if  in  this  way  they  bring  about  a  greater  ingestion 
of  fluids  when  these  are  needed,  their  service  cannot  be 
considered  a  vain  one.  For  it  has  already  been  stated 
that  an  ample  supply  of  drinking  water  or  other  fluids 
taken  daily  and  habitually  is  essential  to  the  satisfactory 
removal  of  the  various  waste  matters  from  the  body,  and 
that  without  it  the  latter  may  readily  develop  conditions 
favoring  disease. 

Moreover,  it  is  true  that  certain  gases  and  salts  held  in 
solution  in  such  beverages  increase  this  excretory  action, 
and  may  be  highly  beneficial  in  appropriate  cases;  but  it 
should  be  a  matter  of  caution  that  where  such  therapeutic 
results  are  thought  to  be  necessary,  competent  medical 
advice  should  be  the  guide  as  to  the  kind  and  quantity  of 
the  agents  used.  This  comment  is  justified  by  the  fact 
that  of  late  many  substances  possessing  decided  physio- 


STIMULANTS  AND  BEVERAGES.  227 

logical  power  have  been  advertised  and  sold  in  the  form 
of  one  beverage  or  another  directly  to  the  laity,  who,  being 
incompetent  to  judge  as  to  whether  or  not  such  substances 
are  actually  needed  in  their  individual  cases,  may  actually 
do  themselves  much  harm  in  this  way. 

Only  such  beverages,  then,  as  are  quite  simple  in  their 
nature  or  as  are  advised  by  competent  medical  authority 
should  be  used.  If  they  are  artificially  made  and  water 
is  the  solvent  fluid,  as  it  will  be  in  most  cases,  there  should 
also  be  certainty  that  it  comes  from  a  clean  and  safe  source, 
lest  it  carry  the  germs  of  disease.  There  is  no  doubt  that 
frequently  the  cheaper  bottled  drinks  which  are  dispensed 
so  generally  are  made  from  water  that  has  been  subject  to 
more  or  less  dangerous  pollution,  and  there  is  the  addi- 
tional risk  that  arises  from  the  imperfect  cleansing  of  the 
bottles  for  these  liquids  which  have  been  returned  to  be  re- 
filled. A  little  thought  as  to  the  dangers  which  do  exist  in 
relation  to  this  matter  will  be  convincing  as  to  their  gravity. 

Many  of  the  most  popular  beverages  are  highly  charged 
with  carbonic-acid  gas  under  pressure,  and  the  fact  that 
so  much  of  this  gas  can  be  taken  into  the  system  in  this 
way  without  apparent  harm,  and  its  free  elimination, 
would  seem  to  be  additional  evidence  that  it  in  itself  could 
not  be  so  very  harmful  in  the  atmosphere,  even  when  in 
proportions  considerably  greater  than  the  normal. 

In  conclusion,  it  may  be  said  that  a  free  use  of  all  such 
beverages  as  are  known  to  be  clean,  safe,  and  wholesome 
will  probably  be  found  to  be  entirely  favorable  to  health, 
unless  there  be  some  contraindicating  reasons  peculiar  to 
the  individual  himself;  and  that  their  substitution  when- 
ever possible  in  place  of  the  alkaloidal  and  alcoholic  stim- 
ulants is  to  be  commended  on  hygienic  as  well  as  other 
grounds. 


CHAPTEK    VIII. 

PERSONAL    HYGIENE. 

THE  proper  consideration  of  this  subject  demands  an 
ample  volume  rather  than  the  limits  of  a  single  chapter, 
for  the  ultimate  aim  of  all  sanitary  work  is  the  preserva- 
tion and  betterment  of  the  health  of  the  individual,  and 
beside,  the  factors  that  affect  the  well-being  of  the  person 
are  so  multitudinous  in  their  number  and  in  their  phases 
that  no  brief  discussion  can  comprehend  them  all. 

However,  much  that  pertains  to  personal  hygiene  and 
that  requires  no  repetition  for  its  application  has  already 
been  given  in  the  preceding  pages;  so  that  it  is  hoped  that 
if  the  reader  will  exercise  that  virtue  of  common  sense 
and  reflection  that  is  so  essential  in  this  study,  the  remarks 
to  be  added  will  be  helpful  in  suggestion  and  in  answering 
many  questions,  even  though  they  may  not  be  considered 
in  any  way  as  complete  discussions  of  the  respective 
themes. 

Each  age  has  its  own  requirements,  and  that  which  may 
be  entirely  satisfactory  or  permissible  at  one  time  may  not 
be  so  at  another.  To  attaiu  the  best  results  it  will  often 
be  necessary  to  even  anticipate  with  prophylactic  measures 
the  birth  of  the  child;  and  broadly  speaking,  much  of  the 
welfare  of  future  generations  lies  in  the  care  of  those  now 
living. 

The  advances  in  physiological  and  biological  science  in 
recent  years  have  done  much  for  all  humanity,  but  in  no 
respect,  perhaps,  have  they  been  of  more  service  than  in 


PERSONAL  HYGIENE.  229 

determining  the  great  influence  of  environment  and  in 
establishing  the  fact  that  the  presence  or  absence  of  dis- 
ease is  oftentimes,  if  not  always,  due  as  much  to  the  pre- 
disposing conditions  and  physical  status  of  the  individual 
as  to  external  and  exciting  causes.  What  may  cause  only 
a  trifling  ill  in  one  may  bring  about  most  serious  evils  in 
another  whose  environment  is  not  so  fortunate. 

Life  has  been  defined  as  the  power  of  an  organism  to 
continually  adjust  its  internal  conditions  to  its  external 
conditions,  and  as  long  as  this  is  done  satisfactorily  life 
persists.  The  secret  of  personal  hygiene  and  health, 
then,  must  lie  in  determining  the  relationship  between 
the  internal  and  external  conditions  of  the  individual's 
organism. 

"  Know  thyself  "  is  advice  good  for  the  body  as  well  as 
for  the  mind  or  soul,  and  knowledge  of  the  right  kind  can 
do  no  harm.  He  who  knows  his  personal  and  physical 
nature  and  acts  accordingly  is  well  equipped  to  fight 
against  the  ills  of  life,  and  the  study  of  the  relationship 
above  referred  to  will  help  the  thinking  man  so  to  care 
for  himself  that  in  all  probability  his  days  will  be  pro- 
longed. 

But  a  caution  or  two  must  be  interpolated  here.  It  is 
well  known  that  "expectant  attention  "  too  persistently 
directed  toward  a  certain  organ  may  lead  to  decided  alter- 
ations or  disturbances  in  the  functions  of  that  organ;  and 
again,  unless  one  well  understands  the  mysteries  of  human 
physiology,  a  little  imperfect  or  insufficient  information  in 
this  respect  may  lead  to  the  assumption  or  pursuit  of  habits 
and  practices  actually  dangerous  to  health .  Too  much  ill- 
advised  care  and  attention  may  be  just  as  full  of  risk  as 
too  little,  and  physiological  egotism  without  a  sound  basis 
may  have  a  bitter  reward. 


230    4  MANUAL  OF  HYGIENE  AND  SANITATION. 

What  is  needed  is  that  each  one  should  study  carefully 
the  phenomena  of  his  daily  life,  should  determine  care- 
fully and  accurately  the  purpose  and  reason  of  each  of 
the  respective  functions,  and  then,  not  forgetting  their 
mutual  interdependence  upon  one  another  and  that  all 
should  work  in  harmony,  should  endeavor  to  do  that 
which  will  best  facilitate  the  functional  activity  with  the 
least  expenditure  of  energy. 

This  may  be  more  or  less  readily  taught  to  and  incul- 
cated in  the  young,  but  with  much  greater  difficulty  can 
we  affect  tie  mature  or  aged;  for  we  are  all  creatures  of 
many  habits,  and  the  impress  of  these  may  resist  to  the 
utmost  any  and  all  endeavors  to  modify  or  remove  them. 

To  quote  what  has  already  been  written:  "  The  essence 
of  sanitation  is  to  secure  perfect  health,  to  increase  the 
inherent  power  to  resist  noxious  and  harmful  influences, 
and  to  make  all  the  surroundings  and  environments  of  the 
body  pure  and  free  from  depressing  factors. " 

With  this  preface,  the  following  discussions  are  added 
in  the  hope  that  they  may  be  of  some  assistance  in  deter- 
mining the  way  of  right  living  and  in  securing  the  welfare 
and  health  of  every  individual. 

Heredity. 

In  the  broadest  sense  heredity  is  a  characteristic  jointly 
possessed  by  two  cells,  furnished  by  respective  parents, 
which  join  and  form  a  fused  cell,  which  carries  on  its 
evolution  under  certain  governing  impressions  indelibly 
stamped  by  the  two  parental  lines  of  descent;  but,  in  the 
ordinary  use  of  the  term,  it  may  be  defined  as  the  trans- 
mission to  the  offspring  from  parent  or  ancestor  of  a  trait, 
type,  temperament,  characteristic,  or  predisposition  which 
has  a  governing  or  influencing  effect  upon  the  growth  or 


PERSONAL  HYGIENE.  231 

nature  of  that  offspring.  This  transmitted  impression 
may  be  either  for  good  or  for  evil.  Consequently,  as  hygi- 
enists,  we  must  use  the  influence  and  power  that  we  have 
to  further  the  transmission  of  beneficial  or  elevating  char- 
acteristics only,  and  to  prevent  the  bequest  of  harmful 
influences  and  hereditary  diseases  to  the  generations  to 
come.  "  The  germ  of  the  unborn  infant  must  be  complete 
and  untainted  in  all  its  nature,  otherwise  we  cannot  hope 
for  a  vigorous  and  perfect  growth  or  development." 

As  the  family  is  the  foundation  of  the  State,  and  society 
is  a  congregation  of  men  for  the  purpose  of  acquiring 
greater  power  and  more  comforts  through  mutual  co-opera- 
tion, the  latter,  whether  domestic  or  civil,  has  some  right . 
to  make  men  understand  that  they  must  care  for  the  health 
of  the  generations  to  follow,  and  to  enact  just  laws  look- 
ing to  the  prevention  or  obliteration  of  transmissible 
infirmities.  And  history  seems  to  show  that  no  great 
nation  has  ever  been  destroyed  or  overwhelmed  until  its 
people  had  first  neglected  or  abused  the  laws  of  hygiene, 
heredity,  and  sociology. 

We  find  that  a  married  couple  have  generally,  beside 
themselves,  the  welfare  of  five  human  beings  within  their 
keeping.  To  produce  healthy  children  and  ones  not  prone 
to  disease  both  parents  should  possess  good  constitutions, 
and  they  should  take  great  care  not  to  weaken  these  by 
excesses  of  any  kind,  physical  or  mental,  nor,  as  far  as 
lies  in  their  power,  by  any  chronic  disease.  It  is  evident 
that  children  of  parents  that  have  been  conscientious 
observers  and  followers  of  Nature's  laws  must  have  a 
better  chance  for  health  and  superiority  all  their  lives. 

In  this  climate  the  proper  age  for  marriage  is  considered 
to  be  about  twenty-four  or  twenty -five  for  the  man,  and 
nineteen  or  twenty  for  the  woman,  though  this  must  vary 


232    ^  MANUAL  OF  HYGIENE  AND  SANITATION. 

with  the  state  of  development  of  the  parties  concerned. 
Some  of  both  sexes  mature  at  a  considerably  earlier  period 
than  do  others,  and  it  would  be  unjust  to  say  that  they 
were  not  fit  for  the  duties  of  marriage  till  they  reached 
the  age  of  slower-growing  ones.  Usually,  however,  before 
the  ages  given,  development  is  not  complete  and  the  whole 
organism  is  in  a  transition  state.  We  know  that  the  use 
of  any  organ  before  it  has  attained  its  complete  growth  or 
development  is  very  apt  to  cause  exhaustion,  or  perhaps 
premature  degeneration  of  that  organ,  and  we  cannot  but 
believe  that  children  developed  in  immature  sexual  organs 
must  be  deficient  in  true  vital  force  and  energy.  It  is 
often  noticeable  that  a  child  apparently  strong  and  vigor- 
ous may  have  but  little  power  to  resist  disease,  or  may  even 
be  strongly  predisposed  to  some  infirmity;  in  such  cases 
there  will  likely  be  some  defect  or  taint  in  the  parent  stock. 

Distinguishing  characteristics  are  more  apt  to  be  trans- 
mitted in  the  early  married  life  of  parents,  because  their 
organs  and  forces  are  then  more  vigorous;  but  if  a  couple 
marry  when  quite  young,  and  before  their  own  organs  are 
fully  developed,  their  elder  children  may  be  more  deficient, 
mentally  and  physically,  than  their  later  ones. 

Late  marriages  are  not  likely  to  be  as  fruitful  as  earlier 
ones,  possibly  owing  to  the  increased  difficulty  of  parturi- 
tion on  the  part  of  the  mother  and  her  consequent  unwil- 
lingness to  undergo  the  ordeal  more  than  a  few  times. 
But  healthy  middle-aged  persons  may  have  even  healthier 
children  than  those  who  have  married  too  early. 

In  features,  constitution,  sense-organs,  shape  of  head, 
etc.,  the  child  is  most  apt  to  resemble  the  father;  while  it 
will  likely  follow  the  mother  in  the  shape  of  the  trunk  and 
in  the  formation  of  internal  organs.  The  character  and 
mental  qualities  of  the  child  may  come  from  either  parent 


PERSONAL  HYGIENE.  233 

or  both.    Maternal  impressions  during  pregnancy  undoubt- 
edly often  have  a  marked  effect  upon  the  coming  infant. 

Hereditary  influences  are  generally  transmitted  directly 
from  parent  to  child,  but  we  occasionally  find  a  cessation 
of  the  trait  or  predisposition  for  one  or  more  generations 
and  then  a  recurrence.  To  such  a  peculiarity  we  give  the 
term  atavism. 

A  disease  may  be  truly  congenital — that  is,  transmitted 
directly  from  parent  to  offspring — as  syphilis,  scrofula, 
etc. ;  or  there  may  be  only  an  inherited  predisposition  to 
the  disease,  as  toward  tuberculosis,  etc.  Physicians  have 
thus  a  twofold  duty :  first,  to  do  all  they  can  to  guard 
against  the  transmission  of  such  diseases;  second,  to  com- 
bat the  disease  or  any  tendency  toward  it  as  soon  as  any 
symptoms  thereof  are  discovered  or  it  is  suspected  in  the 
child.  The  first  duty  can  be  accomplished,  theoretically, 
by  preventing  generation  and  production  on  the  part  of 
those  unfit  to  produce  offspring,  and  practically,  within 
certain  limits,  by  fighting  the  causes  and  their  effects  in 
the  individual,  especially  at  the  ages  or  times  when  these 
have  the  greatest  force  or  are  most  apt  to  manifest  them- 
selves. For  the  second,  the  child  must  be  immediately 
placed  in  the  most  favorable  hygienic  surroundings,  and 
everything  possible  done  to  prevent  the  further  develop- 
ment of  the  disease  or  predisposition.  In  many  cases 
such  early  interference  will  accomplish  much  good,  and  the 
disease  may  be  averted  entirely.  Especially  is  this  true 
of  those  inheriting  the  tuberculous  diathesis. 

The  most  important  of  the  hereditary  or  transmissible 
diseases  are  syphilis,  tuberculosis,  scrofula,  cancer,  gout, 
hysteria,  epilepsy,  certain  physical  deformities,  certain 
skin  diseases,  insanity,  and  criminal  tendencies  of  various 
kinds.  But  what  may  appear  to  be  a  direct  and  actual 


234    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

inheritance  of  a  disease  may  only  be  the  production  of 
the  disease  in  that  person  by  the  same  agents,  environments 
and  morbid  conditions  as  caused  or  favored  the  disease  in 
the  parent.  However,  even  here  there  is  very  possibly  a 
transmitted  predisposition  to  the  acquirement  of  the  dis- 
ease, rendering  it  all  the  more  easy  for  it  to  manifest  its 
symptoms  upon  slight  provocation. 

There  should  be  no  haarriage  between  persons  inheriting 
predispositions  to  the  same  disease,  especially  if  they  be 
relatives,  and  "  a  person  affected  with  hereditary  or  well- 
marked  constitutional  syphilis,  or  having  a  strong  con- 
sumptive taint,  or  tendency  to  mental  unsoundness,  should 
not  marry  at  all." 

Defective  eyesight  is  very  apt  to  be  transmitted  to  chil- 
dren, and  the  latter  should  be  carefully  examined  and,  if 
necessary,  fitted  with  proper  glasses  before  being  placed 
at  school  or  at  any  work  requiring  much  use  of  the  eyes. 

Infirmities  which  do  not  prevent  marriage  from  being 
fully  accomplished,  or  which  do  not  tend  to  the  degenera- 
tion of  the  offspring,  are  not  good  reasons  alone  for  forbid- 
ding marriage,  but  all  that  have  such  a  tendency  are.  A 
man  should  not  marry  a  woman  too  far  advanced  in  life, 
nor  one  that  is  very  feeble,  delicate,  or  deformed,  espe- 
cially as  to  the  chest  or  pelvis.  Hysteria,  convulsions 
and  epilepsy  due  to  organic  disease  should  prevent  a 
woman  from  marrying,  though  some  extremely  nervous 
and  hysterical  women  are  much  benefited  by  marriage,  and 
have  healthy  children.  So  with  many  women  who  have 
uterine  congestions  and  displacements  before  marriage. 

Evidence  seems  to  indicate  that  marriage  between  rela- 
tives is  reprehensible,  the  danger  increasing  with  the  near- 
ness of  relationship,  the  children  of  such  marriage  being 
prone  to  disease  and  to  defects  in  the  sense-organs,  espe- 


PERSONAL  HYGIENE.  235 

cially  the  eye  and  ear,  or  in  mental  qualities.  This  is 
probably  because  the  strong  or  advantageous  points  or 
characteristics  do  not  seem  to  be  transmitted  either  in 
man  or  animals  with  the  same  ease  or  readiness  as  are  the 
faults  or  weaknesses.  However,  any  advice  on  the  subject 
must  depend  upon  the  special  circumstances  in  each  case, 
but  chiefly  on  the  health  and  degree  of  relationship  be- 
tween the  parties. 

Exercise. 

Exercise  is  generally  considered  to  mean  simply  the 
action  of  the  voluntary  muscles,  but  it  has  a  wider  mean- 
ing than  this.  Every  organ  in  the  body  is  capable  of 
being  exercised  in  some  way  or  other;  and  if  not  prop- 
erly exercised  an  abnormal  state  is  almost  certain  to 
ensue.  "  Life  is  organization  in  action."  Each  organ 
has  its  own  special  stimulus,  and  if  this  be  normal  in 
amount  and  character,  we  should  have  health.  Also,  the 
trained  use  of  an  organ  makes  it  more  effective  in  the 
performance  of  its  functions.  But  deficiency  in  exercise 
favors  a  lack  of  nutrition,  wasting  in  size  and  eventually 
degeneration  of  tissue;  while,  on  the  other  hand,  too  much 
work  may  favor  hypertrophy  and  tissue  degeneration. 

Proper  muscular  exercise  is  highly  beneficial  to  health, 
and  in  the  end  actually  necessary  to  the  proper  perform- 
ance of  functions  in  other  organs;  it  is  consistent  with 
and  necessary  to  health.  But,  to  be  of  value,  the  exercise 
must  consist  of  movements  of  sufficient  force  to  necessitate 
energetic  contraction  of  the  muscles;  we  must  do  work. 
This  necessitates  resistance  as  an  element,  and  we  may 
define  physical  exercise  as  voluntary  labor.  We  need  the 
resistance  to  obtain  the  proper  contraction  of  the  muscles, 
the  contraction  for  their  disintegration,  the  disintegration 


236    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

for  their  renewal,  etc. ;  for  we  know  that  upon  the  con- 
stant destruction  and  disintegration  of  tissues  depends 
their  subsequent  renovation,  and  that  the  strength  and 
vigor  of  all  parts  of  the  body  and  of  the  whole  depends 
upon  its  newness. 

Beside  the  fact  that  proper  physical  exercise  makes  the 
voluntary  muscles  larger,  harder,  stronger,  and  more 
quickly  responsive  to  the  will,  and  that  it  increases  the 
functional  capacity  of  the  involuntary  muscles  employed, 
it  largely  promotes  health  and  strength  by  quickening  the 
circulation  and  increasing  the  respiratory  powers.  During 
muscular  action  (contraction)  there  is  a  conversion  of 
potential  energy  into  motion,  a  call  for  more  food,  an 
increased  demand  for  and  consumption  of  oxygen,  and  an 
increased  production  of  and  elimination  of  carbonic  acid 
and  other  waste  matters. 

This  increased  demand  for  oxygen  and  elimination  of 
carbon  dioxide  necessitates  increased  action  of  the  respi- 
ratory organs — the  lungs,  and  this  is  one  of  the  greatest 
advantages  of  physical  exercise.  The  respirations  are  in- 
creased in  frequency  and  depth,  the  lungs  expanded,  the 
air  vesicles  flushed  out  and  refilled  with  each  inspiration. 
Doubtless  many  cases  of  pulmonary  tuberculosis  could  be 
prevented  or  cured  if  only  people  could  be  taught  to  take 
proper  exercise  and  to  breathe  properly,  for  we  rarely  find 
the  lungs  fully  expanded  except  in  the  outdoor  worker  or 
athlete.  Consequently,  the  movements  of  any  given  exer- 
cise should  be  with  speed  and  force  sufficient  to  quicken 
and  deepen  the  respiration;  and,  conversely,  if  any  severe 
exercise  is  to  be  undertaken  or  a  course  of  training  begun, 
especial  care  must  be  had  to  develop  the  lung  capacity. 

A  man  walking  at  the  rate  of  four  miles  per  hour 
inspires  five  times  as  much  air  as  when  reclining  at  rest, 


PERSONAL  HYGIENE.  237 

which  latter  amount  is,  for  an  adult,  about  480  cubic  inches 
per  minute.  Or,  as  Pettenkofer  has  shown,  a  man  on  a 
day  of  rest  absorbs  25  ounces  of  oxygen  and  throws  off 
32  ounces  of  carbon  dioxide  and  29  ounces  of  water;  on  a 
day  of  work  he  absorbs  33.6  ounces  of  oxygen  and  ihrows 
off  45  ounces  of  carbon  dioxide  and  72  ounces  of  water. 
In  other  words,  the  elimination  of  pure  carbon  on  a  work- 
day is  more  than  three-fourths  of  a  pound. 

Muscular  exercise  is  necessary,  therefore,  for  the  proper 
elimination  of  waste  carbon  from  the  body,  and,  as  the 
action  of  the  muscles  is  checked  and  lessened  if  the  carbon 
dioxide  produced  by  their  action  is  not  immediately  carried 
off  by  the  blood  and  eliminated  by  the  lungs,  it  follows  that 
during  exercise  there  should  be  nothing  to  impede  the  cir- 
culation or  the  action  of  the  chest  and  lungs,  and  that  all 
tightness  of  clothing,  especially  about  the  ^aist,  neck,  and 
chest,  should  be  avoided.  Moreover,  inasrr^  stheamount 
of  carbon  dioxide  and  other  waste  mati  -  ;  eliminated  is 
so  very  much  increased  during  exercise,  a  much  larger 
amount  of  pure  air  is  needed,  and  all  rooms  and  buildings 
wherein  exercise  is  to  be  taken  should  be  well  ventilated. 

After  exercise  an  increased  amount  of  carbonaceous  food 
and  of  water  must  be  supplied  to  replenish  the  system  for 
what  has  been  eliminated.  The  increase  of  carbon  is  prob- 
ably best  given  in  the  form  of  fat  rather  than  the  carbo- 
hydrates, though  there  is  some  difference  of  opinion  on  this 
point;  and  of  all  fluids,  water  is  doubtless  the  best  in  ordi- 
nary cases  for  training.  As  a  general  rule,  alcohol  is  harm- 
ful, because  it  benumbs  and  deadens  the  nerves  and  will, 
and,  as  every  voluntary  impulse  must  originate  in  the  brain, 
anything  that  interferes  with  the  communication  between 
it  and  the  muscles  must  lessen  the  promptness  with  which 
they  respond  and  the  consequent  efficacy  of  their  work. 


238    4  MANUAL  OF  HYGIENE  AND  SANITATION. 

The  use  of  a  small  quantity  of  malt  liquor,  however,  as  a 
tonic  or  after  the  exercise  is  finished  may  not  be  harmful, 
but  the  decision  as  to  its  need  or  use  should  be  left  to  the 
physician  or  trainer  rather  than  to  the  one  taking  the 
exercise. 

By  exercise  the  action  of  the  heart  is  increased  in  force 
and  frequency,  the  pulse  is  made  full  and  strong  if  the 
work  be  not  too  excessive  or  sudden,  and  the  flow  of  blood 
and  other  fluids  is  increased  throughout  the  whole  body. 
As  long  as  the  heart  is  not  overtaxed  the  pulse  beats  are 
regular  and  even,  though  suddenly  increased  exertion  may 
make  the  rate  very  rapid.  Ordinary  exercise  increases 
the  rate  from  ten  to  thirty  beats  per  minute.  Excessive 
exercise  leads  to  palpitation  and  hypertrophy  of  the  heart 
(one  reason  why  any  training  should  be  under  a  competent 
trainer) ;  but,  on  the  other  hand,  deficient  exercise  leads  to 
a  weakening  of  the  heart-action,  and  probably  to  dilata- 
tion and  fatty  degeneration.  If  at  the  beginning  of  a  new 
exercise  the  heart-action  becomes  irregular,  rest  should  be 
taken,  and  the  exercise  then  begun  in  a  more  gradual  way. 
The  heart  stimulus  is  due  to  the  increased  amount  of  blood 
in  its  cavities,  but  it  should  be  remembered  that  the  venous 
circulation  is  largely  due  to  the  muscles.  "  Every  muscle 
is  a  little  heart/'  and  these,  by  their  contraction,  con- 
stantly tend  to  drive  the  blood  onward  to  the  true  heart 
and  lungs. 

Exercise  greatly  increases  the  amount  of  perspiration 
from  the  skin,  this  perspiration  containing  water,  salt,  and 
considerable  waste  matter.  The  evaporation  of  the  water 
tends  to  keep  the  body  cool;  but  there  is  not  much  danger 
of  chilling  the  body  during  exercise,  on  account  of  the 
great  heat  production.  As  soon  as  work  is  stopped  heat 
production  is  checked,  the  body  cools  off  rapidly,  and  then 


PERSONAL  HYGIENE.  239 

there  is  danger  of  chilling  unless  more  clothing  be  added. 
Flannel  is  best  for  this,  because  it  is  a  non-conductor  of 
heat,  and  prevents  too  rapid  cooling  of  the  body.  Keep 
the  skin  clean  so  that  the  sweat-glands  may  be  unob- 
structed in  the  performance  of  their  functions. 

Exercise  increases  the  appetite,  partly  because  of  the 
increased  demand  of  the  muscles  for  food  and  partly  on 
account  of  the  increased  circulation  of  the  blood  through 
the  liver  and  the  vessels  of  the  alimentary  tract,  this 
causing  a  more  perfect  digestion  of  food. 

If  exercise  be  taken  too  soon  before  meals  either  the 
stomach,  by  calling  the  blood  from  the  exhausted  muscles, 
will  prevent  their  proper  repair  and  rest;  or  the  muscles, 
calling  the  blood  from  the  stomach,  will  prevent  the  proper 
formation  of  the  gastric  juice  when  food  its  introduced.  If 
exercise  be  taken  too  soon  after  eating,  it  is  apt  to  prevent 
the  flow  of  blood  to  the  stomach  and  the  formation  of 
gastric  juice;  or,  by  forcing  the  contents  of  the  stomach 
into  the  intestines  before  gastric  digestion  is  completed, 
and  before  the  food  has  reached  a  condition  in  which  the 
intestines  can  make  use  of  it,  to  cause  intestinal  irritation 
and  indigestion. 

Proper  physical  exercise  favors  a  symmetrical  brain 
development,  as  exercise  of  the  functions  of  the  centres 
governing  the  action  of  the  muscles  must  favor  the  growth 
and  development  of  those  centres.  "  Hand  culture,  apart 
from  its  value  per  se,  is  a  means  toward  more  perfect  brain 
culture;7'  and  exercise  by  itself  alone  is  truly  educational, 
although  this  feature  of  it  may  be  more  fully  developed 
and  emphasized  by  proper  systems  and  methods.  The 
great  trouble  is  that  it  is  extremely  liable  to  be  misap- 
plied, misunderstood,  or  neglected. 

The  aim  of  training  should  be  to  increase  the  capacity 


240    A  MANUAL  OF  HYGIENE  AND  SANITATION, 

of  the  lungs  and  the  breathing  power,  to  make  the  muscles 
more  powerful,  more  responsive  to  the  will,  and  their 
capacity  for  endurance  greater,  and  to  lessen  the  amount 
of  adipose  tissue.  Systematic  exercise  helps  one  to  resist 
disease,  because  by  it  waste  matters  are  carried  off,  pores, 
glands  and  organs  are  kept  active  and  healthy,  and  active 
tissues  take  the  place  of  weak  and  sluggish  ones. 

Fatigue  is  due  to  lack  of  contractile  material  in  the 
muscles  to  continue  work,  to  the  exhaustion  of  nerve- 
force  and  motor  impulses  from  the  brain,  and  to  accumu- 
lation of  waste  products  in  the  muscle. 

Active  exercise  is  that  brought  about  by  one's  own 
movements ;  passive,  that  produced  by  something  outside 
or  collateral  to  one's  own  power. 

It  is  hard  to  determine  how  much  exercise  any  given 
person  ought  to  take,  as  the  personal  equation  varies  so 
much.  The  average  healthy  man  should  do  work  to  the 
equivalent  of  150  foot-tons  daily.  The  work  of  walk- 
ing on  a  level  at  the  rate  of  three  miles  per  hour  is  said 
to  be  equal  to  that  of  raising  one-twentieth  of  the  body 
weight  through  the  distance  walked.  According  to  this, 
a  man  of  150  pounds  in  walking  one  mile  does  work  equal 
to  17.67  foot-tons,  and  he  would  have  to  do  work  equiva- 
lent to  walking  about  nine  miles  at  the  above  rate  to  get 
the  proper  amount  of  daily  exercise. 

This  seems  like  an  excessive  amount,  but  if  the  work 
done  in  one's  daily  vocation  be  taken  from  this,  it  will  not 
leave  so  very  much  for  the  daily  health-task;  and  while  the 
natural  disinclination  of  many  to  exercise  grows  stronger 
by  indulgence,  and  while  urgent  reminders  are  wanting  and 
the  evils  arising  from  the  neglect,  abuse,  or  misuse  of  exer- 
cise are  not  so  very  immediate  or  apparent,  they  are  still 
certain  and  not  at  all  consistent  with  good  and  perfect  health. 


PERSONAL  HYGIENE.  241 

Bathing1. 

In  health  we  make  use  of  baths  and  bathing  for  the 
cleansing  of  the  body,  the  stimulation  of  the  functions  of 
the  skin,  and  as  a  tonic  to  the  whole  system.  A  proper 
bath  properly  taken  is  exhilarating  and  thoroughly  en- 
joyable. Baths  are  also  to  be  employed  in  sickness  as  a 
means  of  cure,  but  such  use  of  them  is  foreign  to  the 
present  discussion. 

Dr.  H.  C.  Wood  says:  "  Cleanliness  and  the  mainte- 
nance of  the  proper  condition  of  the  skin  require  the  use 
of  the  bath  at  least  twice  a  week.  In  some  very  delicate 
persons  the  general  bath  produces  marked  depression,  but 
this  can  almost  always  be  avoided  by  the  use  of  very  hot 
water.  If  the  hot  or  warm  bath  be  employed  habitually, 
it  should  be  preferably  taken  at  night,  and,  unless  under 
very  exceptional  circumstances,  the  hot  bath  should  always 
be  followed  by  cold  sponging  or  the  cold  shower-bath,  or 
by  a  plunge  into  cold  water. "  The  temperature  of  a  cold 
bath  may  be  from  40°  to  75°  or  80°  F. ;  that  of  a  tepid 
bath,  75°  to  85°  or  90°  F.;  a  warm  one,  85°  to  100°  F.; 
a  hot  one,  from  100°  to  110°  F.,  or  even  hotter.  A  cold 
bath  is  taken  not  so  much  for  its  cleansing  as  its  tonic  and 
stimulating  effects;  the  others  are  used  mainly  for  their 
cleansing  properties,  though  if  followed  by  the  cold 
sponge,  shower,  or  dip  the  sense  of  exhilaration  produced 
will  be  marked. 

Cold  baths  taken  immediately  after  physical  exercise 
while  the  body  is  still  warm,  but  after  perspiration  has 
ceased,  and  followed  by  good  rubbing  and  friction  of 
the  skin,  dispel  fatigue  and  give  a  sense  of  buoyancy 
and  lightness.  The  shock  of  the  first  contact  of  the 
water  to  the  skin  is  but  momentary,  and  can  be  withstood 

16 


242    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

by  most  persons,  unless  there  be  serious  organic  disease; 
and  the  reaction  produced  certainly  compensates  for  the 
momentary  discomfort.  If  the  bath  be  taken  in  the  open 
air,  there  is  the  additional  benefit  of  a  plentiful  supply  of 
fresh  air  for  the  lungs,  of  the  physical  exercise  and 
increased  circulation  induced  by  swimming  or  combating 
the  surf,  and,  if  in  the  sea,  of  the  stimulation  of  the  skin 
by  the  salt.  In  fact,  sea  bathing  may  be  advantageous  to 
a  marked  degree  where  the  circulation  and  action  of  the 
skin  are  sluggish.  Or  a  sea-bath  can  be  imitated  at  home 
by  adding  about  one  pound  of  salt  to  the  gallon  of  water. 

Those  who  are  subject  to  organic  heart  disease  should 
not  indulge  in  sea-bathing  nor  in  deep  fresh-water  bathing 
where  a  sudden  tax  may  be  made  upon  the  strength  and 
the  heart-action  be  disturbed  or  checked.  Women  who 
are  menstruating  or  who  are  in  the  later  months  of  preg- 
nancy should  not  take  cold  baths. 

Baths  should  not  be  taken  too  soon  after  meals,  because 
digestion  may  be  lessened  or  entirely  stopped  by  the  blood 
being  called  from  the  stomach  to  the  skin  and  muscles,  and 
nausea  and  vomiting  thus  induced.  "  There  can  be  no 
doubt  that  many  of  the  cases  that  are  called  e  cramps/ 
and  which  frequently  result  in  drowning,  are  due  to  this 
cause. "'•  In  cold  baths  the  head  should  be  immersed  first, 
i(  to  avoid  increasing  the  blood-pressure  in  the  brain  too 
greatly,  which  might  result  if  the  body  were  gradually 
immersed  from  the  feet  upward.772 

The  following  rules,  issued  by  the  English  Royal  Hu- 
mane Society,  are  worth  noting  :  " Avoid  bathing  within 
two  hours  after  a  meal,  or  when  exhausted  by  fatigue, 
or  when  the  body  is  cooling  after  perspiration.  Avoid 

i  Robe's  Text-Book  on  Hygiene.  2  Ibid. 


PERSONAL  HYGIENE.  243 

bathing  altogether  in  the  open  air,  if,  after  having  been 
a  short  time  in  the  water,  there  is  a  sense  of  chilliness, 
with  numbness  of  the  hands  and  feet;  but  bathe  when 
the  body  is  warm,  provided  no  time  is  lost  in  getting 
into  the  water.  Avoid  chilling  the  body  by  sitting  or 
standing  undressed  on  the  banks  or  in  boats  after  having 
been  in  the  water.  Avoid  remaining  too  long  in  the 
water,  but  leave  the  water  immediately  if  there  is  the 
slightest  feeling  of  chilliness.  The  vigorous  and  strong 
may  bathe  early  in  the  morning  on  an  empty  stomach; 
the  young  and  those  who  are  weak  had  better  bathe  two 
or  three  hours  after  breakfast.  Those  who  are  subject  to 
giddiness  or  fainting,  or  suffer  from  palpitation  or  other 
sense  of  discomfort  of  the  heart,  should  not  bathe  (out  of 
doors)  without  first  consulting  their  physician."1 

After  any  kind  of  a  bath  the  body  should  be  thoroughly 
dried,  not  only  to  restore  and  accelerate  the  circulation  of 
the  skin  by  the  friction  and  to  prevent  the  cooling  by  the 
evaporation  of  the  water,  but  also  to  prevent  chafing  and 
eczematous  eruptions  where  the  skin  is  subject  to  friction 
of  clothing.  Warm  or  hot  baths  should  not  be  taken  if 
the  person  is  to  be  exposed  to  the  cold  within  several 
hours,  and  the  same  rule  applies  to  Turkish,  Russian,  and 
vapor  baths:  so  these  latter  should  not  be  taken  away  from 
home  in  cold  weather,  unless  the  bather  takes  pains  to  rest 
well  after  the  bath,  and  then  to  wrap  up  well  before  going 
into  the  open  air. 

In  all  warm  baths  in  health  the  principal  object  is  to 
secure  the  cleansing  effects,  and  to  be  effective  their  use 
must  be  systematic.  The  pores  of  the  skin  are  self- 
cleansing  only  to  a  certain  degree,  and  the  free  use  of 

1  See  also  "  Sea  Air  and  Sea  Bathing,"  by  Dr.  John  H.  Packard. 


244    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

warm  water  is  most  beneficial  in  removing  dry  epithe- 
lium, sweat,  dirt,  and  grease.  If  the  pores  of  the  skin 
are  obstructed  there  are  not  only  irritation  and  eruptions 
of  the  skin  produced,  but  more  work  is  thrown  upon  the 
kidneys,  and  these  if  affected  will  break  down  the  quicker. 
Soft  water  is  to  be  preferred  for  ordinary  bathing  and 
washing,  because  it  often  prevents  or  reduces  cutaneous 
irritation,  and  because  it  saves  soap. 

A  Turkish  bath  consists  :  1.  Of  a  dry,  hot-air  bath  at  a 
temperature  of  from  120°  to  170°  F.,  or  even  higher,  from 
ten  to  thirty  minutes.  This  causes  in  most  persons  ex- 
treme perspiration,  with  no  sense  of  discomfort,  but  rather 
a  very  pleasant  sensation.  After  this  come  :  2.  A  hot 
shower-bath  to  wash  off  the  sweat.  3.  Shampooing, 
massage,  and  scrubbing,  to  thoroughly  remove  all  dirt, 
loose  epithelium,  and  perspiration  from  the  skin.  This 
is  in  moist  air  at  from  100°  to  110°  F.  4.  A  warm 
shower-bath  gradually  changing  to  a  cold  one,  and  then 
a  thorough  drying  of  the  body  and  a  rest  for  a  quarter  or 
half  an  hour.  A  Russian  bath  differs  from  this  only  in 
that  moist  air  at  150°  F.,  or  less,  is  used  instead  of  dry 
air  for  the  first  bath. 

It  has  been  said  "  that  a  person  ought  never  to  stay  in 
either  the  hot  air  or  steam-room  if  in  any  wise  oppressed, 
or  to  use  very  cold  water  afterward  if  one  feels  any 
shrinking  from  it."  Nor  should  one  who  is  very  corpu- 
lent or  subject  to  organic  heart  disease  take  a  Turkish  or 
Russian  bath  without  the  advice  of  a  physician.  But  for 
healthy  persons  they  are  very  pleasant,  and  in  most  cases 
beneficial,  provided  they  are  not  taken  too  often  and  that 
one  does  not  indulge  in  them  too  long  at  a  time. 

The  terms  sun-,  mud-,  sand-,  and  pine-needle  baths  are 
self-explanatory.  These  are  used  in  treating  certain  di&- 


PERSONAL  HYGIENE.  245 

eases,  and  are   supposed  to  do  some  good,  especially  in 
rheumatic  affections. 

Clothing. 

There  is  scarcely  anything  that  can  be  said  on  this 
subject  with  which  almost  every  one  of  ordinary  intelli- 
gence is  not  in  some  respects  conversant.  According 
to  Dr.  Poore,  the  main  objects  to  be  sought  in  clothing 
the  body  are:  "  1.  To  maintain  the  temperature  and,  by 
preventing  the  loss  of  animal  heat,  to  diminish  to  some 
extent  the  demands  for  food.  2.  To  allow  the  chief  heat- 
regulating  mechanism — z.  e.,  the  evaporation  from  the 
skin — to  proceed  with  as  little  hinderance  as  possible.  3. 
To  allow  all  muscular  acts  the  greatest  possible  freedom, 
and  to  avoid  the  compression  of  the  body  in  so  far  as  may 
be  possible.  4.  To  protect  the  body  from  heat,  cold, 
wind,  and  rain.  5.  To  disguise  as  little  as  may  be  the 
natural  beauties  of  the  human  figure/'1 

The  substances  from  which  articles  of  clothing  are 
usually  manufactured  are  wool,  silk,  cotton,  linen,  leather, 
and  furs,  although  almost  everything  that  can  possibly  be 
fashioned  to  suit  the  needs  or  fancies  of  the  wearer  is  or 
has  been  utilized  for  the  purpose.  Goods  of  all  manner 
and  kind  are  woven  from  the  first  four  substances  men- 
tioned, either  singly  or  in  combination  one  with  another, 
and  felts  are  made  from  wool,  hair,  or  fur,  these  latter 
being  made,  not  by  weaving,  but  by  an  interlacing  and 
matting  together  of  the  fibres  by  pressure  and  rubbing. 

In  a  general  sense  wool  is  probably  the  most  valuable 
of  clothing  materials,  in  that  in  a  variable  climate,  or  where 
there  are  sudden  changes  of  temperature,  it  is  the  safest  for 

1  Stevenson  and  Murphy :  Treatise  on  Hygiene. 


246    ^  MANUAL  OF  HYGIENE  AND  SANITATION. 

the  wearer  to  use.  While,  taking  fibre  for  fibre,  it  prob- 
ably does  not  vary  so  much  from  linen  or  cotton  as  a  heat 
conductor  as  is  generally  believed,  it  is  usually  woven  in 
such  a  way  as  to  entangle  large  quantities  of  air  in  its 
meshes,  thus  preventing  either  sudden  cooling  or  heating  ; 
and  beside,  it  is  extremely  hygroscopic,  taking  up  water  and 
perspiration  very  readily  and  giving  them  off  slowly,  thus 
reducing  the  cooling  by  evaporation  to  a  minimum  and 
regulating  the  heat-dissipation  of  the  body.  All  who  are 
at  all  subject  to  rheumatism  or  to  such  symptoms  as  are 
dependent  on  sudden  temperature  changes  should  wear 
woollen  garments  next  to  the  skin  the  year  round,  varying 
the  thickness  and  weight,  of  course,  to  suit  the  season,  and 
children  and  others  subject  to  digestive  disturbances  will 
usually  be  greatly  benefited  by  the  constant  use  of  woollen 
(or,  in  case  that  is  too  heavy,  a  silken)  band  about  the 
abdomen. 

As  it  is  ordinarily  woven,  some  persons  cannot  tolerate 
wool  next  to  the  skin  on  account  of  its  irritating  proper- 
ties. These  latter  are  obviated,  however,  if  the  undergar- 
ments be  made  of  pure  wool  woven  by  methods  similar  to 
that  introduced  by  Dr.  Jaeger,  or  of  a  mixture  of  wool 
and  cotton.  The  Jaeger  method,  by  the  way,  provides  for 
the  escape  of  moisture  from  the  material  and  for  the  air 
permeating  freely  through  its  interstices. 

Silk  is  a  good  non-conductor  of  heat,  and  is  almost  as 
hygroscopic  as  wool,  so  that  it  is  good  material  from  which 
to  make  warm  clothing.  Its  great  natural  beauty  and  the 
facility  with  which  it  takes  coloring  matter  also  make  it 
desirable  from  an  aesthetic  stand-point,  but  its  great  disad- 
vantage is  its  high  cost.  For  those  who  cannot  wear  wool 
next  the  skin  and  to  whom  the  cost  is  no  objection,  silk  is 
an  excellent  material  for  undergarments. 


PERSONAL  HYGIENE.  247 

Cotton  is  probably  the  most  generally  used  for  clothing 
of  all  the  fibres.  It  is  hard  and  durable,  is  not  as  hygro- 
scopic by  far  as  wool,  and  is,  above  all,  cheap,  so  that  it 
furnishes  the  -bulk  of  the  clothing  for  the  masses.  If 
smoothly  woven  and  of  a  light  color,  it  makes  extremely 
cool  garments  for  warm  climates  or  seasons.  On  the  other 
hand,  if  warm  clothes  are  desired,  the  cotton  must  be 
woven  so  as  to  have  large  air  spaces  in  the  fabric,  the  air 
acting  as  an  especially  good  non-conductor  of  heat  and 
preventing  the  lowering  of  the  body  temperature.  Cotton 
should  not  be  worn  next  the  skin  by  those  subject  to  sud- 
den temperature  changes,  nor  during  exercise,  unless  it  is 
changed  in  the  latter  case  immediately  after  the  exercise, 
or  some  additional  clothing  is  added  to  the  body  to  prevent 
too  rapid  evaporation  and  cooling. 

Linen  is  valued  for  its  purity  of  color  when  bleached, 
and  for  its  durability.  It  is  more  expensive  than  cotton, 
but  its  hygroscopic  and  heat-conducting  properties  are 
about  the  same  as  the  latter.  It  is  especially  desirable  for 
making  clothing  for  hot  climates  and  for  articles  of  dress 
that  are  easily  soiled  and  need  frequent  cleansing. 

Furs  provide  extreme  protection  against  the  wind  and 
cold,  both  on  account  of  the  impermeability  of  the  skin 
and  of  the  large  quantity  of  air  entangled  in  the  fur  itself. 

Leather  is  utilized  for  foot-coverings,  etc. ,  on  account  of 
its  durability,  pliability,  and  practical  imperviousness  to 
moisture,  especially  when  oiled;  and  in  cold  countries  is 
also  used  for  body  garments,  on  account  of  its  resistance 
to  the  wind  and  the  efficacy  with  which  it  keeps  the  body 
surrounded  with  a  layer  of  warm  air. 

With  the  possible  exception  of  rubber,  which  is  especially 
useful  for  the  protection  which  it  gives  from  wet  and  wind 
and  rain,  other  materials  from  which  clothing  is  made  need 


248    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

not  be  mentioned  here,  because  of  the  comparative  rarity 
of  their  use  and  their  close  resemblance  to  those  already 
mentioned.  The  value  of  any  material  for  clothing  pur- 
poses, however,  may  be  said  to  depend  upon  the  slowness 
with  which  it  permits  the  passage  of  heat  to  or  from  the 
body  and  the  evaporation  of  water,  the  amount  of  air  its 
meshes  contain,  its  impermeability  to  the  wind,  or  else  its 
special  adaptability  to  some  special  purpose. 

Certain  materials  are  manufactured  from  combinations 
or  mixtures  of  two  or  more  of  the  four  fibres  first  men- 
tioned, and  it  sometimes  become  necessary  to  distinguish 
these  one  from  another  and  to  determine  the  proportion  of 
each  in  the  goods.  This  is  done  by  microscopical  exami- 
nation, each  fibre  having  its  own  peculiar  characteristics, 
and  by  chemical  reactions.  Some  of  these  latter  are  as 
follows:  Wool  and  silk  dissolve  in  hot  liquor  potassae  or 
sodse  of  a  specific  gravity  of  1050,  while  cotton  and  linen  are 
not  affected.  Wool  and  silk  are  stained  yellow  by  strong 
nitric  or  picric  acid;  cotton  and  linen  are  not.  Sulphuric 
acid  affects  wool  but  little,  slowly  dissolves  silk,  and 
changes  cotton  or  linen  into  a  gelatinous  substance  that  is 
colored  blue  by  iodine.  Hot  concentrated  zinc  chloride 
dissolves  silk,  but  not  wool;  and  copper  dissolved  in  am- 
monia rapidly  dissolves  silk  and  cotton,  linen  more  slowly, 
but  only  swells  the  wool  a  little. 

Cloths  are  often  fraudulently  sophisticated  in  the  process 
of  manufacture,  and  their  value  greatly  lessened  thereby. 
Wool  is  mixed  with  "shoddy,"  which  is  made  from  old  and 
used  woollen  rags,  torn  asunder  and  then  respun  with  an 
addition  of  fresh  wool;  silk  is  heavily  weighted  with  salts 
of  tin,  iron,  or  with  other  substances,  and  cotton  and  linen 
are  stiffened  and  glossed  with  an  excessive  amount  of 
starch,  white  earth,  or  the  like.  Shoddy  can  be  deter- 


PERSONAL  HYGIENE,  249 

mined  by  the  use  of  the  microscope;  the  weighting  of  silk 
by  chemical  reactions  and  solutions;  and  overstarching, 
etc.,  of  cotton  and  linen  by  washing  and  drying. 

It  will  not  be  advisable  here  to  go  into  the  consideration 
of  the  influence  which  the  shape  and  style  of  the  individ- 
ual garments  of  ordinary  use  have  upon  health,  for  that 
would  require  a  much  longer  discussion  than  the  present 
space  would  allow  ;  but  the  general  rule  may  be  laid 
down  that  each  article  of  clothing  should  be  adapted  to 
the  peculiar  needs  and  occupation  of  the  wearer,  and  that 
it  should  in  no  wise  interfere  with  the  proper  develop- 
ment, use,  or  physiological  functions  of  any  part  of  the 
body. 

When  exposed  to  the  sun's  rays  or  to  other  sources  of 
radiant  and  incandescent  heat,  fabrics  absorb  heat,  irre- 
spective of  the  constituent  materials,  but  in  the  following 
order  as  regards  color  :  White,  light  yellow,  dark  yellow, 
light  green,  Turkey  red,  dark  green,  light  blue,  and  black, 
the  latter  color  absorbing  more  than,  and  light  blue  almost 
twice  as  much  as  white,  the  material  in  each  case  being 
the  same.  In  the  shade  the  absorption  depends  more  on 
the  material  than  on  the  color. 

Lastly,  it  should  be  remembered  that,  as  disease  germs 
are  readily  conveyed  from  place  to  place  and  from  one 
person  to  another  by  the  clothing,  and  especially  by  that 
which  is  hygroscopic  by  nature,  care  should  be  taken  to 
keep  the  garments  in  as  cleanly  and  aseptic  condition  as 
possible,  to  disinfect  them  whenever  they  have  been  ex- 
posed to  infection,  and,  for  those  who  are  much  among  the 
sick  or  liable  to  infection,  the  use  of  smooth,  closely  woven, 
non-hygroscopic  over  or  outer  garments  that  can  be  readily 
cleansed,  such  as  cotton  or  linen,  is  to  be  highly  recom- 
mended. 


250    ^  MANUAL  OF  HYGIENE  AND  SANITATION. 

Light. 

The  important  influence  of  sunlight  in  the  development 
and  maintenance  of  a  healthful  condition  in  all  higher 
organisms,  both  animal  and  vegetable,  is  well  known  by 
every  one;  but  as  yet  there  is  a  lack  of  information  as  to 
the  exact  physiological  methods  and  processes  which  are 
due  to  this  great  force.  We  know  that  for  the  plants 
chlorophyll  is  the  intermediary  agent  which  largely  assists 
in  the  conversion  of  carbonic  acid  and  the  storage  of  carbon 
in  various  compounds,  and  that  the  presence  and  action  of 
this  chlorophyll  are  largely  dependent  upon  the  light- 
supply;  while  for  the  animal  kingdom,  and  especially  for 
the  human  race,  it  is  evident  that  the  effect  of  sunlight  is 
manifested  more  or  less  directly  upon  the  blood  and  skin, 
though  the  whole  body  quickly  manifests  a  marked  appre- 
ciation of  its  presence  or  absence.  But  when  this  has 
been  said,  there  is  little  else  that  can  be  added  as  a  matter 
of  positive  information.  No  one  knows  just  how  the 
pallid  and  anaemic  child  that  has  been  reared  in  the  shade 
and  dark  can  be  converted  into  the  tanned  and  ruddy 
picture  of  health  in  so  short  a  time,  but  the  results  are 
unquestionable. 

The  subject  demands  much  further  study,  and  it  may 
not  be  out  of  place  to  indicate  one  or  two  directions  in 
which  the  investigation  may,  perchance,  be  wisely  pursued. 

In  the  first  place,  there  has  doubtless  been  too  little 
appreciation  of  the  fact  that  the  sunlight  in  its  totality 
has  many  other  rays  of  force  than  those  which  manifest 
themselves  alone  to  our  sense  of  sight.  The  existence  of 
the  ultra-violet  rays  and  the  fact  that  these  are  more 
powerful  actinically  than  those  of  the  ordinary  spectrum 
have  been  satisfactorily  demonstrated,  and  the  only  ques- 


PERSONAL  HYGIENE.  251 

tion  is  as  to  what  the  true  power  and  influence  of  these 
invisible  rays  may  be.  It  is  not  certain  as  yet  that  some 
of  them,  at  least,  are  not  closely  related  to  the  new  mani- 
festation of  force  discovered  so  recently  by  Rontgen,  and 
there  is  good  reason  to  believe  that  the  penetrative  powers 
of  light  as  regards  the  human  body  are  not  yet  fully 
known  or  appreciated.1  Nor  can  we  tell  how  much  of 
that  power  of  the  sun  whose  effects  we  feel  and  see  is  in 
nature  on  that  borderland  between  light  and  electricity 
that  is  as  yet  so  vague  and  unknown. 

Again,  the  destructive  effect  of  sunlight,  and  of  light 
from  minor  sources  as  well,  upon  the  germs  of  disease  and 
other  low  forms  of  life,  is  now  a  matter  of  common  knowl- 
edge, though  many  are  not  aware  that  it  has  been  proven 
that  this  germicidal  action  of  light  is  directly  in  relation 
to  its  actinic  power.  Considering  this,  with  the  statements 
of  the  preceding  paragraph,  may  we  not  surmise  that  hostile 
organisms,  even  in  the  deeper  tissues,  are  overcome  both 
in  this  way  and  by  the  improved  condition  of  the  blood 
due  to  the  light,  and  that  this  helps  to  explain  the  good 
results  that  follow  the  open-air  treatment  of  many  diseases 
and  abnormal  conditions  ?  The  tubercle  bacilli  are  espe- 
cially susceptible  to  its  influence,  and  every  one  knows  that 
an  abundance  of  sunlight  is  just  as  essential  to  the  tuber- 
culous patient  as  is  plenty  of  good  food,  pure  air,  or  proper 
clothing. 

More  might  also  be  said  in  reference  to  the  possible  and 


1  Some  experiments  by  the  author  and  by  numerous  others  seem  clearly  to  in- 
dicate that  some  of  the  radiant  energy  from  the  sun,  and  in  lesser  degree  from 
other  sources  of  light,  is  able  to  penetrate  substances  hitherto  considered  opaque 
and  to  produce  phenomena  similar  to  those  due  to  the  Rontgen  ray.  Conse- 
quently, if  the  experiments  referred  to  are  well  founded,  the  penetrative  ability 
of  this  energy,  as  regards  the  human  tissues,  would  seem  to  be  more  than  prob- 
able. 


252    ^  MANUAL  OF  HYGIENE  AND  SANITATION. 

probable  chemical  activity  of  the  light  in  and  upon  the 
metabolic  processes  of  the  animal  body;  but  as  there  is 
still  the  uncertainty  of  hypothesis  and  theory,  it  may  be 
wiser  to  simply  leave  the  foregoing  suggestions  as  food  for 
thought  and  incentives  to  further  research  and  investiga- 
tions. 


CHAPTER    IX. 

SCHOOL    HYGIENE. 

IT  might  have  been  remarked  in  the  chapter  on  Per- 
sonal Hygiene  that  the  best  time  for  applying  and  observ- 
ing the  laws  of  hygiene  is  in  the  days  of  childhood  and 
youth,  for  then  the  whole  organism  is  plastic  and  yields 
readily  to  both  external  and  internal  impressions  and 
forces. 

This  being  so,  the  great  influence  of  the  factors  common 
to  school  life  may  be  readily  conceived,  and  inasmuch  as 
the  average  child  will  be  subject  to  them  for  a  large  part 
of  from  eight  to  ten  or  more  years,  the  importance  of  a 
study  of  school  hygiene  will  not  be  denied.  It  concerns 
the  parent,  the  physician,  and  the  citizen,  and  its  investi- 
gations must  consider  the  personal  hygiene  of  the  scholar, 
the  condition  of  his  health,  his  habits,  the  amount  of 
work  done,  the  sanitary  environment  and  requirements  of 
the  school-room  or  building,  the  furniture,  the  ventilation 
and  heating,  and  the  influence  of  all  these  upon  the  indi- 
vidual's state  and  development. 

Next  to  the  scholar  himself  and  his  parents,  these  mat- 
ters are  of  especial  interest  to  the  physician,  for,  beside 
being  one,  who  from  his  special  training  and  education  is 
often  called  to  act  upon  school  committees  and  boards  of 
education,  he  has  to  treat  many  disturbances  of  health  in 
the  young  which  have  their  origin  or  cause  in  the  harmful 
or  insanitary  conditions  of  school  life. 

There  are  disturbances  to  which  all  children  are  subject, 


254    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

whether  in  school  or  out;  but  a  special  class  are  markedly 
influenced  by  school  life  or  work,  and  to  these  abnormal 
conditions  we  may  give  the  term  "School  Pathology. " 
Of  some  of  these  overwork  is  the  cause;  others  are  set  up 
by  other  factors. 

Overwork,  coupled  with  depressed  vitality,  may  give  rise 
in  children  to  one  or  more  of  the  following  troubles  :  Dys- 
pepsia, headaches,  nervous  derangements,  chorea,  epilepsy, 
neurasthenia,  backaches,  menstrual  disorders,  and,  in  some 
cases,  consumption.  On  the  other  hand,  bad  arrangement 
of  seats  and  desks,  improper  location  of  windows,  black- 
boards, etc. ,  may  cause  spinal  and  other  physical  deformi- 
ties, defective  eyesight,  etc.  Of  the  first  class,  even  where 
the  amount  of  work  may  not  seem  or  may  not  really  be 
too  much  for  the  capacity  of  the  child,  worry  about  rank 
or  over  an  approaching  examination  may  have  a  harmful 
effect  upon  a  nervous  temperament.  This  is  especially  so 
if  the  examinations  come  at  the  end  of  a  spring  term, 
when  the  scholars  are  all  more  or  less  worn  out  and  debili- 
tated. The  forcing  process  should  be  avoided  as  far  as 
possible,  and  if  grades  are  to  be  given  at  all,  they  should 
be  as  much  as  possible  for  the  work  and  attendance  during 
the  term,  and  not  so  much  for  the  actual  work  done  at 
examination  time. 

Moreover,  young  children  should  not  be  kept  in  school 
for  too  many  hours  in  the  day,  nor  should  the  school  be 
looked  upon  by  parents  as  a  place  to  which  to  send  chil- 
dren to  keep  them  out  of  the  way  and  from  mischief. 
Edwin  Chadwick  has  shown  that  a  child  from  five  to  seVen 
years  can  only  attend  to  one  subject  for  about  fifteen  min- 
utes; one  from  seven  to  ten,  for  twenty  minutes;  from  ten 
to  twelve,  for  twenty-five  minutes,  etc.,  and  that  the  length 
of  individual  lessons  and  likewise  the  total  day's  work 


SCHOOL  HYGIENE.  255 

should  be  arranged  accordingly.  The  very  early  years  of 
school  life  should  be  given  to  inculcating  correct  habits  of 
attention  and  of  morals  and  to  training  the  will  and  power 
of  concentration,  rather  than  to  the  teaching  of  any  special 
knowledge. 

But  it  is  probably  the  work  attempted  outside  after 
school  hours,  and  not  the  actual  work  done  in  the 
school,  that  is  most  responsible  for  the  breaking  down 
of  health,  especially  in  older  scholars.  In  Cleveland,  in 
1881,  of  186  girls  in  the  high  school,  29  per  cent,  of  those 
who  studied  less  than  two  hours,  70  per  cent,  of  those 
studying  from  two  to  four  hours;  93  per  cent,  of  those 
studying  from  four  to  six  hours,  and  100  per  cent,  of  those 
studying  over  six  hours  daily  out  of  school,  had  poorer 
health  while  at  school.  Of  these  same  girls,  the  percent- 
ages of  those  whose  health  was  "  very  poor  while  at 
school/ '  dividing  them  the  same  way  as  regards  over- 
work, were  respectively  14  per  cent.,  40  per  cent.,  66  per 
cent.,  and  100  per  cent.  This  loss  of  health  was  attributed 
by  the  parents  to  stair-climbing,  irregularity  of  meals, 
worry  about  rank  and  examinations,  etc.,  but  Dr.  Goodell 
says:  ((  So  commonly  do  I  find  ill  health  associated  with 
brilliant  scholarship,  that  one  of  the  first  questions  I  put 
to  a  young  lady  seeking  my  advice  is,  '  Did  you  stand 
high  at  school  ??  '  Another  writer  says  :  ' '  The  effects  of 
anxiety  are  worse  than  carrying  heavy  loads." 

While  a  child  is  at  school  its  mind  should  not  be  wea- 
ried by  outside  tasks,  as  music  or  painting  lessons,  nor  the 
body  weakened  by  social  dissipations,  late  hours,  and  indi- 
gestible food.  Girls  are  more  susceptible  to  disturbances, 
and  are  more  subject  to  them,  because  they  are  more  will- 
ing to  undertake  extra  or  double  work  than  boys,  and 
because  they  are  more  ambitious  and  worry  more  about 


256    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

rank.  In  all  children  the  obtaining  of  good  health  and 
a  sound  constitution  is  of  the  first  importance.  Youth  is 
the  time  for  gaining  health,  not  for  losing  it;  for  building 
up  sound  bodies  and  constitutions,  not  for  breaking  them 
down,  and  school  life  should  always  have  the  former  as 
one  of  its  greatest  ends.  Of  what  use  is  all  the  learning 
one  may  gain  before  the  age  of  eighteen,  if  there  be  no 
strength  to  use  it  afterward  in  the  battle  of  life  ? 

School-life  is  sometimes  responsible  for  dyspepsia  by 
interfering  with  the  regularity  of  meals,  the  children  miss- 
ing the  midday  meal  and  having  to  depend  upon  a  meagre 
lunch,  often  of  sweets  and  indigestible  food.  This  is  espe- 
cially important  when  the  rest  of  the  family  dine  at  noon, 
and  there  is  only  a  light  meal  served  in  the  evening. 
Again,  many  habitually  lose  their  breakfast  through  fear 
of  being  late,  or  else  bolt  the  food  without  masticating  it, 
and  gulp  down  hot  coffee  or  tea  before  starting  on  a  run 
for  school.  But  often  the  loss  of  appetite  is  due  simply 
to  lack  of  fresh  air  and  proper  exercise.  Such  dyspepsias 
are  to  be  treated  by  attention  to  the  foregoing  points  rather 
than  by  medicine. 

Headache  is  a  common  disturbance  among  school  chil- 
dren, and  may  be  due  to  any  one  of  several  causes,  among 
which  are  overwork — producing  irritability  and  disturb- 
ances of  cerebral  circulation — bad  air,  eye-strain,  etc.  The 
eyes  should  always  be  examined  when  headaches  are  per- 
sistent, and  any  defects  corrected  by  proper  glasses.  Asso- 
ciated with  the  headaches  frequent  bleeding  from  the  nose 
may  occur,  and  should  not  be  overlooked,  as  it  may  in- 
dicate circulatory  disturbance. 

One  of  the  most  common  symptoms  of  nervous  derange- 
ment is  sleeplessness  or  restless  sleep,  and  this  condition 
should  give  warning  that  something  is  wrong.  Dr.  Folsom 


SCHOOL  HYGIENE.  257 

says:  "I  doubt  whether  there  is  an  exaggerated  preva- 
lence of  manifest  or  well-marked  diseases  of  the  nervous 
system  among  school  children.  If  due  to  the  school- drill, 
my  impression  is  that  they  come  for  the  most  part  later  in 
life,  after  the  children  have  left  school,  and  because  of 
constitutions  weakened  during  school  years,  instead  of 
strengthened  as  they  should  be."  Children  subject  to 
chorea  or  epilepsy  should  not  attend  school,  not  only  for 
their  own  sake,  but  for  that  of  the  other  children,  who 
may  be  unduly  affected  by  their  nervous  manifestations. 
They  should  be  educated  quietly  and  cautiously,  with 
proper  treatment  and  plenty  of  outdoor  life.  Neurasthe- 
nia or  general  break-down  may  occur,  usually  from  over- 
work, and  especially  among  young  women.  It  may  come 
on  unexpectedly  after  the  examinations,  when  the  strain 
and  excitement  are  removed.  Menstrual  disorders  are  also 
apt  to  occur  among  girls  that  are  being  overworked  men- 
tally, and  we  ought  to  remember  that  at  the  time  this 
function  is  developing  the  system  is  undergoing  a  heavy 
strain.  Also,  to  certain  women  rest  from  customary  work 
is  necessary  at  the  time  of  the  periodical  recurrence,  and 
excuses  for  absence  at  this  time  ought  to  be  freely  granted. 
It  has  been  said  that  "  girls  get  through  as  much  work  as 
boys,  working  in  their  own  way." 

The  development  of  consumption  may  be  due  to  the 
school-life,  though  it  is  hard  to  say  how  frequently  this  is 
the  case.  Bad  air  and  overwork  are  both  important 
factors  in  its  production,  and  if  these  are  forced  on  under- 
fed or  predisposed  children  the  disease  may  be  provoked. 
"  In  a  consumptive  family  the  steadfast  rule  should  be 
that  the  mind  be  wholly  subservient  to  the  body's  welfare." 

The  main  cause  of  spinal  and  other  deformities  and 
defective  eyesight  is  apt  to  be  found  in  faulty  construction 

17 


258    A.  MANUAL  OF  HYGIENE  AND  SANITATION. 

of  seats  and  desks,  improper  location  of  windows,  etc., 
though  excessive  work  or  strain  may  maintain  a  low  vitality 
and  act  as  a  predisposing  condition.  The  latter  point  is 
shown  by  the  fact  that  spinal  curvatures  are  more  preva- 
lent in  those  especially  prone  to  weakness  of  the  muscles, 
as  women  and  girls. 

But  no  desk  or  seat  will  remove  original  weakness  of 
muscle  as  the  one  important  predisposing  condition,  and 
children  cannot  be  made  strong  by  supports.  <e  Spinal 
curvature  is  not  only  a  product  of  low  vitality,  but  does 
harm  by  permanently  fixing  vitality  at  a  low  standard. " 
Bad  seats  and  desks  not  only  cause  spinal  deformities,  but 
help  to  cause  defective  eyesight  by  making  the  scholar 
hold  the  book  too  near  the  eyes  and  by  making  him  bend 
his  head  so  that  the  circulation  of  blood  is  impeded  and 
ocular  congestion  favored.  However,  no  seat  can  be  de- 
vised in  which  a  child  will  maintain  a  correct  or  "  normal " 
position  for  any  length  of  time,  as  this  is  an  impossibility 
for  young  children;  but  the  true  aim  should  be  to  furnish 
a  seat  in  which  one  will  naturally  assume  the  correct  posi- 
tion after  having  temporarily  taken  any  other.  "  Move- 
ment is  a  child's  way  of  resting;  rest  is  a  kind  of  work, 
to  be  taught  by  degrees. "  Seats  should  have  backs  to 
prevent  fatigue,  but  a  comfortable  back  gives  support  to 
the  lower  part  of  the  spine  rather  than  to  the  shoulders 
and  upper  part  of  the  spine.  Many  foregin  authorities 
advise  seats  with  backs  only  high  enough  to  support  the 
lower  part  of  the  spine,  and  low  enough  for  the  scholar  to 
rest  his  elbows  upon  them  while  studying.  The  following 
points,  suggested  by  Dr.  Lincoln,  are  worth  noting  :  "  1. 
The  chair  is  often  too  high  for  young  scholars.  The  most 
convenient  plan  may  be  to  provide  footstools.  2.  The  seat 
from  back  to  front  ought  to  be  long  enough  to  support  the 


SCHOOL  HYGIENE.  259 

whole  thigh.  A  more  or  less  spoon-shaped  hollow  in  the  seat 
is  commonly  thought  desirable.  The  curve  of  many  settees 
is  such  as  to  produce  pain  at  the  point  where  the  tuberosi- 
ties  of  ischium  rest  on  the  wood;  the  support  is  there  not 
wide  enough.  3.  Seats  must  have  backs.  The  straight, 
upright  back  reaching  to  the  shoulders  is  bad;  a  straight 
back,  slightly  tilted,  is  not  bad.  American  seats  are  com- 
monly curved,  with  curved  backs.  4.  The  edge  of  the 
desk  should  come  up  to,  or  overlap,  the  edge  of  the  seat. 
The  recognition  of  this  fact  is  a  recent  discovery.  5.  Most 
of  our  best  desks  are  too  high  relatively  to  the  seat,  doubt- 
less to  prevent  the  pupil  from  stooping.  Something  is 
gained  in  convenience  of  reading  by  this  plan,  but  it  in- 
terferes with  correct  positions  in  writing.  The  elbows, 
hanging  freely,  should  be  only  just  below  the  level  of 
the  lid."  For  near-sighted  children  the  higher  desk 
may  be  a  necessity  in  writing;  if  the  desk  is  made  low  a 
portable  writing-stand  may  be  placed  on  top  of  it  when 
necessary. 

Windows  on  only  one  side  of  a  large  school-room  may 
not  give  sufficient  light  for  the  desks  most  remote  from 
them.  Consequently,  there  should  be  windows  on  two 
sides,  preferably  adjoining  ones,  of  large  school-rooms. 
The  windows  should  be  at  the  back  and  to  the  left  of  the 
scholar,  thus  giving  the  best  light  upon  the  desk  for  either 
reading  or  writing.  They  should  not  be  placed  in  front  of 
the  scholars,  as  the  continuous  light  and  glare  is  very  try- 
ing and  injurious  to  the  eyes.  They  should  extend  almost 
to  the  ceiling  and  have  square  tops,  to  admit  of  as  much 
light  as  possible.  Blackboards  should  have  a  dead-black 
surface,  not  a  glossy  one,  and  should  be  on  the  sides  of 
the  room  on  which  there  are  no  windows.  Walls  should 
be  of  a  neutral  tint,  not  glaring  white. 


260    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

Construction  of  School-houses.  The  principles 
already  given  as  to  ventilation,  heating,  water-supply, 
etc.,  apply  here  as  elsewhere.  From  1800  to  2500  cubic 
feet  of  fresh  air  should  be  supplied  to  each  scholar  per 
hour.  In  cold  weather  this  should,  of  course,  be  satis- 
factorily heated.  The  air-ducts,  both  inlets  and  outlets, 
must  be  large  enough  to  change  the  air  without  causing 
injurious  and  uncomfortable  draughts;  and  these  ducts 
should  be  as  short  and  free  from  bends  as  possible,  or  better, 
the  rooms  should  open  into  the  supply  and  exhausts  shafts 
directly.  The  air  may  be  warmed  either  by  steam  or 
hot-water  coils  or  by  a  furnace,  though  preferably  by  the 
former,  to  avoid  "  baking  "  the  air,  and  also  preferably  by 
the  indirect  system.  There  is  no  objection  to  having  addi- 
tional heating  apparatus  in  the  school-room,  provided  it  is 
guarded  so  that  the  scholars  may  not  be  accidentally 
burned.  Any  system  that  will  give  a  sufficient  supply  of 
fresh  air  properly  heated  will  of  necessity  be  more  expen- 
sive than  the  old  way  of  not  ventilating  at  all  except  by 
opening  the  windows  at  recess  time,  but  experience  shows 
that  the  increase  in  expense  is  not  so  very  great,  as  so 
much  heat  is  lost  by  opening  the  windows  in  this  way, 
and  the  benefit  to  the  children  more  than  compensates  for 
the  additional  outlay.  Country  schools  may  be  heated 
by  stoves  surrounded  by  sheet-iron  drums,  and  ventilated 
with  fresh  air  brought  in  from  without  near  the  bottom 
of  the  stove.  Passing  up  between  the  stove  and  drum 
the  air  is  warmed  and  gives  good  ventilation  without 
chilling  or  draught.  As  great  a  length  of  stovepipe  should 
be  exposed  as  possible,  to  get  the  full  benefit  of  the  heat 
from  it. 

The  school-house  should  be  on  dry  and  well-drained 
soil,  as  dampness  is  not  only  depressing  to  all  constitu- 


SCHOOL  HYGIENE.  261 

tions,  but  is  an  important  factor  in  the  causation  of  phthisis 
and  strumous  diseases.  There  should  not  be  too  much 
shade  about,  and  as  many  rooms  as  possible  should  have 
sunny  exposures.  If  the  sun  is  annoying  during  the  ses- 
sion, it  may  be  excluded  by  inside  blinds  or  shutters,  but 
we  must  not  lose  sight  of  its  helpful  influence  in  the  de- 
struction of  bacteria  and  purification  of  organic  matters. 
Basements  of  school-houses  should  be  well  lighted,  water- 
tight and  dry,  and  should  be  kept  scrupulously  clean,  that 
moisture  and  noxious  gases  may  not  be  drawn  into  the 
rooms  above.  If  properly  arranged  and  cared  for^  they 
may  be  used  as  play-rooms  in  bad  weather  when  it  would 
be  unwise  to  send  the  scholars  out  of  doors. 

The  water-supply  should  be  free  from  all  impurities  and 
as  good  as  can  be  had.  In  the  country,  if  from  a  neigh- 
boring farm-house  spring  or  well,  it  may  be  contaminated 
by  leakage  from  cesspools  and  barnyards.  Or  the  school 
water  may  be  taken  from  a  neighboring  spring  or  stream 
which  is  receiving  contamination  from  the  school-house 
cesspool  or  other  sources.  For  this  reason,  teachers  should 
be  taught  to  make  the  test  for  chlorides  and  the  reason 
for  it,  and  should  make  this  test  frequently.  If  cause  for 
suspicion  arises  the  use  of  the  water  should  be  stopped  at 
once. 

Water-closets  and  urinals,  where  in  use,  should  be  kept 
clean  by  a  competent  janitor,  and  the  principal  or  head- 
teacher  should  see  that  this  is  done.  In  the  country,  the 
pail  or  earth-closet  system  should  be  substituted  for  the 
usual  privy-vault  or  cesspool,  and  it  should  be  the  duty  of 
some  one  apart  from  the  teacher,  regularly  appointed  and 
paid  by  the  school  directors  of  the  district,  to  see  that 
removals  are  made  at  proper  intervals;  the  teacher  should 
maintain  supervision  over  the  daily  condition  of  affairs. 


262    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

If  possible,  the  out-houses  should  be  connected  with  the 
school-house  by  covered  ways,  that  the  children  may  not 
be  exposed  in  inclement  weather;  but  these  ways  should 
be  open  or  else  constantly  ventilated  by  open  windows  on 
either  side.  Cesspools  should  be  at  least  fifty  feet  distant, 
and  should  drain  away  from  the  school-house. 

Ample  provision  must  be  made  for  the  rapid  escape  and 
for  the  safety  of  scholars  and  teachers  in  case  of  fire  or 
panic.  Fire-drills  should  be  regularly  practised  in  all 
schools  of  two  stories  or  more,  and  presence  of  mind  incul- 
cated, that  emergencies  may  be  met  with  safety.  The 
comfort  of  the  child  should  not  be  forgotten  in  the  con- 
struction of  the  school-house,  though  preservation  of 
health  is  the  main  aim. 

School  Quarantine.  As  certain  diseases  are  conta- 
gious, it  is  necessary  that  school  authorities  have,  a  right 
to  forbid  the  attendance  of  such  persons  as  have  been 
exposed  to  infection  until  all  danger  of  transmitting  the 
disease  to  others  is  passed.  This  power  is  usually,  how- 
ever, exerted  only  in  the  case  of  those  diseases  most  dan- 
gerous to  life  and  health,  though  the  stringency  of  the 
regulations  varies  at  different  places.  Smallpox,  scarlet 
fever,  diphtheria,  measles,  and  even  whooping-cough  ought 
always  to  be  quarantined,  and  it  would  be  better  to  keep 
children  out  of  school  who  are  afflicted  with  minor  dis- 
eases of  this  class  till  all  danger  of  infection  is  over, 
as  it  is  only  by  rigid  measures  like  this  that  we  may 
finally  be  able  to  wipe  those  maladies  out  of  existence. 
Local  boards  of  health  should  make  and  enforce  rules 
looking  to  the  prevention  of  the  spread  of  the  graver 
contagious  diseases,  and  should,  when  necessary,  close 
schools  and  school- buildings  till  all  danger  is  past.  Dr. 
Lincoln  gives  the  following  as  a  system  of  general  regu- 


SCHOOL  HYGIENE.  263 

lations:  "  1.  Persons  affected  with  diphtheria,  measles, 
scarlet  fever,  or  smallpox  (varioloid)  must  be  excluded 
from  the  schools  until  official  permission  is  given  by  the 
board  of  health  for  their  readmission.  2.  Persons  living  in 
a  family  or  house  where  such  a  case  occurs  are  also  excluded 
until  similar  permission  is  given.  3.  This  permission  is 
not  to  be  given  until  sufficient  time  has  elapsed  since  the 
occurrence  of  the  last  case  to  insure  safety,  nor  until  the 
premises  have  been  disinfected  under  the  direction  of  the 
board  of  health.  4.  If  a  child  suffering  from  one  of 
the  above  diseases  attends  school,  the  premises  of  the 
school  must  be  disinfected  under  the  direction  of  the  board 
of  health  before  they  are  used  again.  5.  Physicians, 
teachers,  school  officers,  and  school  "children  knowing  of 
such  cases  of  disease  should  at  once  report  them  to  the 
board  of  health.  6.  The  board  should  also  notify  the 
school  authorities  of  all  such  cases.  7.  Notice  must  be 
sent  to  the  family  by  the  school  authorities,  acting  con- 
jointly with  the  board  of  health." 

Children  having  had  one  of  the  above-named  diseases 
may  return  to  the  school  with  safety  after  the  following 
periods:  "  Scarlet  fever,  six  weeks  from  date  of  rash,  pro- 
vided desquamation  and  cough  have  ceased.  Smallpox 
and  chicken-pox,  when  every  scab  has  fallen.  Whooping- 
cough,  after  six  weeks  from  commencement  of  whooping, 
provided  the  characteristic  spasmodic  cough  and  whooping 
have  ceased,  or  earlier  if  all  cough  have  passed  away. 
Diphtheria,  not  less  than  three  weeks,  if  convalescence 
is  completed;  there  being  no  longer  any  form  of  sore 
throat  nor  any  kind  of  discharge  from  the  throat,  nose, 
eyes,  ears,  etc.,  nor  any  albumin uria."  Rules  and  regu- 
lations like  the  above,  when  promulgated,  "  should  have 
the  force  and  authority  of  law,  and  should  be  enforced,  if 


264    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

necessary,  by  the  entire  power,  including  school  officers, 
etc.,  of  the  State/'  It  is  to  be  hoped  that  we  shall  soon 
have  a  means  of  inoculating  persons  against  all  contagious 
diseases,  as  we  now  do  against  smallpox.  At  present 
boards  of  health  and  school  boards  should  insist  on  the 
vaccination  of  all  school  children.  In  Illinois,  from  1880 
to  1883,  .the  deaths  from  smallpox  among  un vaccinated 
children  were  48  per  cent.;  among  the  vaccinated,  only 
0.9  per  cent.  In  this  city  all  who  desire  it  are  vaccinated 
free  of  charge  by  the  vaccine  physicians,  and  it  is  com- 
pulsory for  all  school  children. 

Regulations  similar  to  the  following,  suggested  by 
Lincoln,  should  be  in  force  in  every  school  district : 
((  Every  child  entering  the  public  schools  must  show  a 
certificate  from  some  reputable  physician,  giving  name, 
age,  residence,  approximate  date  of  vaccination,  date  of 
examination,  result  of  examination,  the  last  two  to  be  of 
the  physician's  own  knowledge.  The  fact  of  vaccination 
must  be  entered  on  the  school  record  and  on  lists  for  pro- 
motion and  transfer.  The  school  authorities  shall  annu- 
ally report  the  number  of  those  not  protected  to  the  State 
Superintendent  of  Education.  School  authorities  may 
order  the  exclusion  of  non-protected  persons,  after  suffi- 
cient notice,  where  they  think  the  measure  required  for 
the  public  health.  He- vaccination  at  the  age  of  fifteen 
may  be  required  under  similar  circumstances.  Those 
unable  to  pay  should  be  furnished  with  free  vaccination 
by  the  school  authorities.  A  physician's  certificate  of 
protection  by  a  previous  attack  of  smallpox  is  equivalent 
to  a  certificate  of  vaccination." 

Contagious  ophthalmia  is  a  disease  often  prevalent  in 
institutions  and  occasionally  in  primary  schools,  and  re- 
quires great  care  to  prevent  its  invasion  and  spreading,  as 


SCHOOL  HYGIENE.  265 

well  as  to  effect  a  cure.  Those  afflicted  with  it  should  be 
quarantined  until  there  is  no  further  discharge  or  till  the 
granulations  on  the  inner  surface  of  the  eyelids  have  disap- 
peared. Enfeebled  health  and  poor  and  insufficient  food 
favor  its  development,  but  the  chief  means  of  contagion 
is  by  the  use  of  the  same  wash-basins  and  towels  by  a 
number  of  children. 

School  children  should  not  be  allowed  to  attend  the 
funerals  of  companions  dead  of  a  contagious  disease,  nor 
should  funerals  be  allowed  in  school-houses  under  any 
circumstances,  owing  to  the  effect  on  the  thoughts  and 
sensibilities  of  nervous  children. 

Boarding-schools  and  institutions  should  have  an  in- 
firmary where  contagious  diseases  may  be  isolated,  and 
should  make  that  isolation  as  complete  as  possible  from 
other  scholars  and  inmates.  At  the  beginning  of  a  term  it 
may  be  well  to  subject  any  who  have  been  exposed  to  conta- 
gion to  a  delay  until  the  probable  period  of  incubation  for 
the  special  disease  is  passed,  the  period  dating  from  the  time 
of  exposure.  With  the  above  precautions  it  will  rarely 
be  necessary  to  close  a  school,  unless  a  disease  be  markedly 
epidemic  and  malignant. 


CHAPTEK  X. 

DISINFECTION   AND    QUARANTINE. 

As  has  already  been  stated,  disinfection  is  that  part  of 
prophylaxis  which  has  to  do  with  the  destruction  or  modi- 
fication of  the  exciting  causes  of  disease,  and  we  may 
accordingly  define  a  disinfectant  as  "  an  agent  capable  of 
destroying  the  infective  power  of  infectious  material." 
Moreover,  as  with  our  present  knowledge  we  are  practi- 
cally limited  in  the  use  of  disinfection  to  the  infectious 
diseases  only,  a  disinfectant  must  also  be  a  germicide. 
Theoretically,  it  should  also  have  the  power  of  destroying 
the  poisonous  properties  of  the  toxins  which  the  disease 
germs  produce,  and  which  create  the  characteristic  symp- 
toms of  the  specific  diseases;  but  whether  all  good  disin- 
fectants have  this  power  is  by  no  means  proven,  and  is 
not  altogether  essential,  since  by  killing  the  germs  we 
check  the  further  production  of  the  toxins,  and  disinfect- 
ants are  mainly  used  not  so  much  to  cure  or  stop  a  disease 
in  a  patient  as  to  prevent  its  extension  to  others.  But,  in 
a  popular  sense,  the  term  disinfection  is  given  a  wider 
meaning  than  is  above  indicated,  including  not  only  the 
use  of  antiseptics  and  deodorants,  but  often  the  actual  re- 
moval of  filth  and  all  matters  favorable  to  the  growth  or 
spread  of  disease  germs.  It  is  needless  to  say  that  these 
latter  may  be  part  of  the  prescribed  duties  of  a  disinfector, 
but  are  not  the  essential  functions  of  a  disinfectant. 

It  will  be  well  here  to  make  the  distinction  between 
disinfectants  and  antiseptics  and  deodorants,  as  the  terms 


DISINFECTION  AND  QUARANTINE.  267 

are  often  wrongly  used  interchangeably,  and  there  is  a 
common  belief  that  whatever  is  a  deodorant  or  an  anti- 
septic is  also  a  disinfectant.  An  antiseptic  is  an  agent  that 
retards  or  arrests  bacterial  growth  and  the  consequent  pro- 
duction of  toxins  or  ptomaines,  though  it  does  not  neces- 
sarily kill  the  micro-organisms  themselves;  and  though 
some  antiseptics  are  germicidal,  others  are  not  and,  there- 
fore, as  a  class  they  cannot  be  considered  or  used  as  dis- 
infectants. But,  on  the  other  hand,  "  agents  which  kill 
bacteria  in  a  certain  amount  prevent  the  multiplication  of 
the  latter  in  culture  fluids,  when  present  in  quantities 
considerably  less  than  are  required  to  destroy  vitality.7' 
So,  a  diluted  germicide  may  act  as  an  antiseptic  and  may 
be  used  therefor.  For  instance,  chlorinated  lime,  which 
is  a  good  disinfectant  in  solutions  of  proper  strength,  may 
arrest  further  bacterial  growth  or  action  in  a  mass  of 
sewage  or  filth  and  prevent  the  latter  acting  as  a  culture- 
medium  for  disease  germs,  even  though  the  agent  be 
totally  inadequate  in  quantity  to  kill  all  the  micro-organ- 
isms' present.  In  the  same  way,  it  may  act  as  a  deodorant 
— which,  by  the  way,  is  an  agent  that  simply  removes  or 
destroys  offensive  odors,  and  is  not  necessarily  either  a 
disinfectant  or  an  antiseptic — both  by  checking  the  further 
action  of  saprophytic  bacteria  and  the  formation  of  putre- 
faction odors,  and  by  actually  decomposing  and  oxidizing 
those  of  the  latter  already  formed. 

In  practical  disinfection  it  is  also  well  to  remember  that 
while  masses  of  dead  organic  matter  may  not  in  some  cases 
contain  disease  germs  and  may  be  even  hostile  to  them,  in 
general  the  reverse  of  this  is  more  likely  to  be  true,  and 
decaying  matter  often  furnishes  a  good  field  for  the  increase 
of  pathogenic  organisms.  Moreover,  the  noxious  gases 
given  off  to  the  air  and  the  poisonous  products  added  to  the 


268    ^  MANUAL  OF  HYGIENE  AND  SANITATION. 

drinking-water  from  such  masses  may  also  do  much  harm 
by  depressing  the  system,  lowering  the  vitality,  and  acting 
as  predisposing  conditions  to  the  incurrence  of  such  filth 
diseases  as  cholera,  yellow  fever,  typhoid  and  typhus  fever, 
diphtheria,  etc. ;  and  when  time  or  opportunity  do  not 
permit  of  the  removal  of  such  dangerous  accumulations, 
their  power  for  harm  should  be  checked  permanently  or 
temporarily  by  the  use  of  suitable  disinfectants  or  antisep- 
tics. 

But  when  we  are  actually  dealing  with  disease  germs, 
disinfection,  to  be  trustworthy,  must  be  carried  out  to  the 
best  of  our  ability  with  the  means  at  our  command  and 
with  strict  attention  to  the  minutest  details.  "  There  can 
be  no  partial  disinfection  of  infectious  material ;  either  its 
infectious  power  is  destroyed  or  it  is  not.  In  the  latter 
case  there  is  a  failure  to  disinfect/7 

This  is  because  the  undestroyed  living  bacteria  still  have 
the  power  of  reproduction,  and  may,  within  a  very  short 
time  under  favorable  circumstances,  equal  or  even  exceed 
the  number  that  was  present  before  the  unsuccessful  disin- 
fection was  attempted. 

The  knowledge  as  to  the  efficacy  of  any  substance  as  a 
disinfectant  is  obtained  from  the  accumulated  experience 
of  practical  sanitarians  and  from  experiments  on  suscep- 
tible animals  and  in  culture  media. with  infectious  matter 
treated  with  presumably  disinfecting  agents.  The  knowl- 
edge gained  must  stand  the  test  of  scientific  deduction, 
and  a  substance  is  not  a  disinfectant  simply  because,  in 
one  given  case,  infection  did  not  occur  after  its  use.  To 
be  of  value  the  deductions  must  be  made  from  considerable 
accumulated  and  practical  experience.  "  Negative  evi- 
dence should  be  received  with  great  caution ;"  but  if  the 
experience  of  practical  sanitarians  is  confirmed  by  careful 


DISINFECTION  AND  QUARANTINE.  269 

culture  and  inoculation  experiments,  our  knowledge  of 
the  value  of  any  agent  becomes  more  definite  and  our 
practical  work  more  exact.  From  these  inoculations  and 
experiments  it  has  been  found  that  the  infectious  germs  of 
different  diseases  differ  in  their  power  to  resist  the  different 
disinfectants;  but  nevertheless  it  may  be  stated  that  "  in 
the  absence  of  spores,  a  disinfectant  for  one  is  a  disinfec- 
tant for  all."  Consequently,  we  are  able  to  simplify  and 
classify  the  agents  at  our  disposal,  and  to  make  more 
effectual  use  of  them.  Note  that  there  is  nothing  in  the 
tests  mentioned  to  disprove  the  efficacy  of  disinfectants, 
whatever  the  nature  of  the  infecting  material,  and  whether 
the  germ  theory  be  accepted  or  not. 

Some  agents  that  are  powerful  against  all  other  organ- 
isms completely  fail  in  destroying  the  vitality  of  spores, 
and  thus  our  list  of  disinfectants  available  in  all  cases  is 
still  further  reduced.  In  the  case  of  a  disease  germ  that 
does  not  produce  spores,  as  that  of  cholera,  and  probably 
also  of  scarlet  fever,  smallpox,  yellow  fever,  etc.,  agents 
may  be  used  that  are  really  powerless  against  spores,  but 
in  doubtful  cases  only  those  should  be  used  that  have  the 
power  of  spore  destruction. 

We  may  classify  the  disinfectants  of  which  we  may 
make  practical  use  as  thermal  or  chemical,  though  there 
are  undoubtedly  certain  secretions  and  tissues  in  the  body 
which  have  the  power  of  destroying  infective  matters, 
giving  each  person  more  or  less  immunity  against  certain 
diseases,  and  these  we  may  term  physiological  disinfectants. 

Of  the  thermal  disinfectants  fire  is  the  most  efficacious, 
as  it  destroys  all  organic  matter,  but  it  can  only  be  used  to 
destroy  articles  of  little  value  or  that  cannot  be  safely 
disinfected  in  any  other  way.  For  instance,  it  will  usually 
cost  more  than  they  are  worth  to  disinfect  thoroughly  by 


270    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

other  methods  old  mattresses  that  have  been  used  in  an 
infectious  case,  so  it  is  best  to  burn  them. 

All  things  considered,  steam  is  probably  the  most  efficient 
disinfectant,  as  it  is  cheap,  easily  used  and  manipulated, 
and  is  less  liable  to  injure  the  articles  to  be  disinfected. 
We  employ  it  under  pressure,  when  its  temperature  is 
correspondingly  increased,  or  in  the  streaming  state  (live 
steam),  the  latter  being  almost  as  efficient  as  the  former, 

FIG.  35. 


Steam  sterilizer  for  small  articles. 


but  requiring  a  little  longer  time.  For  instance,  steam  at 
240°  F.  is  said  to  kill  the  most  resistant  spores  almost 
instantly,  and  streaming  steam  at  212°  F.  will  probably 
produce  the  same  effect  within  thirty  or  forty  minutes. 
Special  apparatus  for  disinfecting  large  articles  by  steam 
is  now  or  doubtless  soon  will  be  established  in  every  large 
city  by  the  municipal  authorities  and  others,  as  a  sanitary 
precaution  and  to  prevent  the  spread  of  epidemics. 


DISINFECTION  AND  QUARANTINE. 


271 


In  the  absence  of  spores,  bacteria  are  killed  by  hot  water 
even  below  the  boiling  point,  and  it  is  probably  safe  to  say 
that  boiling  for  half  an  hour  will  kill  all  known  disease 
germs,  especially  if  a  little  washing  soda  be  added  to  the 
water;  although  spores  of  certain  harmless  bacilli  are  said 
to  have  resisted  boiling  for  several  hours.  In  the  absence 
of  chemical  disinfectants,  boiling  water  may  be  used  to 


FIG.  36. 


Steam  disinfecting  chamber  for  clothing,  bedding,  and  other  large  articles. 

disinfect  excreta,  etc.,  and  all  clothing  from  the  sick  or 
the  attendants  upon  the  sick  should  be  well  boiled  before 
washing,  whether  other  disinfectants  are  used  or  not. 

Dry  heat  is  far  less  penetrating  than  moist,  and  must, 
accordingly,  be  used  at  much  higher  temperatures  and  for 
a  longer  time.  At  300°  F.  it  will  require  three  or  four 
times  as  long  to  do  what  steam  at  212°  or  220°  F.  will 
do,  and,  moreover,  it  is  very  apt  to  injure  clothing  or  other 


272    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

organic  materials  exposed  to  it  at  high  temperatures  for  so 
long  a  time  as  is  necessary.  Consequently,  it  is  only  to  be 
used  to  disinfect  articles  that  would  be  spoiled  by  moisture 
or  chemicals,  and  even  then  it  is  better  to  employ  the 
"  fractional ' '  method — i.  e.,  exposure  to  high  tempera- 
tures for  short  periods  only,  but  for  a  number  of  times, 
with  sufficient  intervals  between  the  exposures  to  allow 
the  development  of  any  spores  that  may  possible  be 
present. 

Regarding  the  chemical  disinfectants,  it  must  be  remem- 
bered that  it  requires  a  certain  amount  of  each  to  disinfect 
a  given  quantity  of  bacteria,  and  also  that,  with  all  disin- 
fectants, time  is  an  important  element,  and  none  act  abso- 
lutely instantaneously.  Heat,  however,  facilitates  and 
increases  the  rapidity  of  action  of  the  chemical  disinfect- 
ants. 

Chlorinated  lime  (chloride  of  lime)  is  one  of  the  best  and 
cheapest  disinfectants.  It  should  contain  at  least  25  per 
cent,  of  available  chlorine,  should  be  kept  covered  from 
air  and  moisture,  and  fresh  solutions  should  always  be 
made  as  needed.  Its  power  is  due  to  hypochlorite  of 
lime,  which  is  freely  soluble  in  water  and  readily  decom- 
poses in  contact  with  organic  matter,  giving  up  chlorine 
gas — a  most  powerful  disinfectant.  "  Germs  of  all  kinds, 
including  the  most  resistant  spores,  are  destroyed  by  this 
solution  ;  but  it  must  be  remembered  that  the  disinfectant 
itself  is  quickly  decomposed  and  destroyed  by  contact  with 
organic  matter,  and  that  if  this  is  present  in  excess,  disin- 
fection may  not  be  accomplished,  especially  when  the 
germs  are  imbedded  in  masses  of  material  which  are  left 
after  the.hypochlorite  of  lime  has  been  all  exhausted  in  the 
solution/7  Labarraque's  solution,  a  solution  of  chlorinated 
soda,  is  a  fair  disinfectant,  but  does  not  keep  well,  and 


DISINFECTION  AND  QUARANTINE.  273 

chlorinated  lime  is  equally  as  good  and  much  cheaper. 
However,  the  soda  solution  has  scarcely  any  diagreeable 
odor,  and  makes  a  pleasant  disinfecting  bath  for  the  person. 
It  must  contain  at  least  3  per  cent,  of  available  chlorine. 

Bichloride  of  mercury  is  one  of  the  best  germicides  that 
we  have,  and  is  effective  in  comparatively  weak  solutions. 
It  corrodes  metal,  and  so  cannot  be  used  to  disinfect  waste- 
pipes,  etc. ;  and  it  combines  with  and  coagulates  albumin, 
which  interferes  somewhat  with  its  action.  This  coagula- 
tion is  prevented  to  a  degree  by  the  addition  of  tartar ic 
acid  to  the  disinfecting  liquid.  The  same  result  is  said  to 
be  obtained  if  one  part  of  peroxide  of  hydrogen  (fifteen 
volume  solution)  be  added  to  three  parts  of  a  corrosive 
sublimate  solution  of  any  strength.  But  for  the  above 
reason  it  is  best  not  to  use  corrosive  sublimate  in  disin- 
fecting excreta,  as  these  always  contain  more  or  less  albu- 
min, and  a  lime  solution  is  better  and  more  certain.  As 
carbolic  acid  also  coagulates  albumin,  it  is  not  well  to  use 
it  for  a  like  purpose. 

Carbolic  acid  is  effective  in  the  absence  of  spores,  and, 
according  to  Koch,  should  have  first  place  in  disinfection 
against  the  cholera  germ.  It  is  of  doubtful  value,  how- 
ever, in  cases  of  typhoid  fever,  as  it  is  said  that  the  typhoid 
bacilli  can  be  cultivated  in  a  medium  containing  J  per 
cent,  of  carbolic  acid.  Solutions  should  always  be  made 
by  first  dissolving  the  acid  in  glycerin,  and  should  usually 
contain  5  per  cent,  of  acid. 

Copper  sulphate  is  a  fairly  good  disinfectant  in  the 
absence  of  spores;  is  a  deodorant,  and  is  cheap.  It  may 
be  combined  with  bichloride  of  mercury  to  color  the  solu- 
tion of  the  latter  and  to  get  the  benefits  of  its  deodorant 
powers,  which  the  corrosive  sublimate  does  not  have.  Use 
may  be  made  of  the  following  formula:  Corrosive  subli- 

18 


274    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

mate  (bichloride  of  mercury),  4  ounces;  copper  sulphate, 
1  pound;  water,  1  gallon. 

Zinc  chloride  is  a  good  antiseptic  and  deodorant,  but  not 
a  very  powerful  disinfectant.  A  5  or  10  per  cent,  solu- 
tion will  kill  germs  without  spores. 

Calcium  hydrate,  when  mixed  with  water  to  make  a  thin 
whitewash  (milk  of  lime),  is  said  to  be  a  good  disinfectant, 
especially  for  excreta,  etc.,  and  is  one  of  the  cheapest  and 
easiest  to  obtain.  It  should  be  added  to  the  infectious 
matter  in  excess  or  until  the  mixture  is  decidedly  alkaline, 
and  will  require  from  one-half  to  two  hours  to  disinfect 
thoroughly. 

An  extremely  valuable  disinfectant  for  local  or  topical 
applications  to  the  person  is  hydrogen  peroxide  or  dioxide 
(H2O2).  It  is  harmless,  even  when  taken  internally;  is 
effective  in  comparatively  weak  solutions,  and  is  especially 
active  in  the  destruction  of  pus  organisms.  It  is  usually 
supplied  in  the  form  of  a  15  per  cent,  solution  in  water 
and,  at  present,  only  its  high  cost  prevents  its  more  ex- 
tended use. 

Until  the  discovery,  in  1892,  of  the  great  disinfecting 
power  of  formaldehyde  or  formic  aldehyde  by  Trillat  and 
Aronson,  about  the  only  gaseous  disinfectants  of  practical 
value  were  chlorine  and  sulphur  dioxide. 

Of  these,  chlorine  is  the  most  powerful  and  efficient, 
but  the  distressing  and  oftentimes  serious  symptoms  which 
it  produces  when  accidentally  inhaled,  and  the  bleaching 
effect  that  it  has  upon  many  articles,  have  both  tended 
to  prevent  its  common  employment.  Like  the  sulphur 
dioxide,  it  acts  best  in  the  presence  of  moisture,  and,  there- 
fore, steam  should  be  simultaneously  introduced  and  liber- 
ated in  the  room  or  enclosure  in  which  either  of  these 
disinfectants  is  used.  Sufficient  chlorine  for  1000  cubic 


DISINFECTION  AND  QUARANTINE.  275 

feet  of  space  may  be  generated  by  carefully  pouring  two 
fluidounces  of  strong  sulphuric  acid  and  three  fluid- 
ounces  of  water,  previously  mixed  and  cooled,  upon  eight 
ounces  of  sodium  chloride  (common  salt)  and  two  ounces 
of  manganese  dioxide.  The  acid  must  be  added  to  the 
water  little  by  little  and  with  care,  and  the  salt  and  man- 
ganese should  be  in  an  earthen  vessel  upon  a  bed  of  sand, 
to  prevent  injury  to  the  floor  or  carpet. 

Sulphur  dioxide  (SO2),  though  not  so  positive  in  its  action 
as  chlorine,  is  more  frequently  employed  on  account  of  the 
lesser  risk  and  trouble  connected  with  it.  It  probably 
kills  germs  not  containing  spores  if  sufficiently  concen- 
trated and  in  the  presence  of  moisture,  and  is,  therefore, 
useful  in  the  fumigation  of  rooms  and  of  articles  that 
cannot  be  subjected  to  steam  heat  or  chemical  solutions. 
But  it  will  bleach  or  tarnish  many  articles,  and  for  this 
reason  and  the  fact  that  it  is  much  inferior  to  formalde- 
hyde, it  will  hereafter  probably  be  almost  entirely  sup- 
planted by  the  latter  whenever  that  can  be  obtained. 

To  secure  sufficient  concentration  at  least  three  pounds 
of  sulphur  should  be  burned  for  every  1000  cubic  feet  of 
space,  care,  of  course,  being  had  that  there  is  no  risk  of 
igniting  the  floor  or  any  articles  in  the  room. 

Formaldehyde  (formic  aldehyde),  both  in  its  gaseous  state 
and  in  solution,  is  undoubtedly  one  of  the  best  and  most 
efficient  disinfectants  now  in  use.  It  has  considerable 
penetrating  power,  although  less  than  steam  or  than  was 
claimed  for  it  at  first  by  its  more  enthusiastic  advocates, 
while  for  surface  disinfection  it  acts  almost  immediately. 
It  is,  therefore,  much  better  in  this  respect  than  the  chlo- 
rine or  sulphur  dioxide  already  mentioned,  and  where  it  is 
properly  used,  only  such  articles  as  bedding,  mattresses, 
and  pillows,  that  can  be  better  treated  with  steam,  need  be 


276     A  MANUAL  OF  HYGIENE  AND  SANITATION. 

removed  from  an  infected  apartment.  Clothing,  rugs, 
hangings,  etc.,  that  can  be  freely  exposed  to  it  are  quickly 
sterilized.  Another  important  feature  is  that  it  does  not 
act  destructively  on  either  clothing  or  furniture,  and  that, 
although  it  is  quite  irritating  to  the  conjunctivas  of  the 
eyes  and  to  other  mucous  membranes  when  concentrated, 
it  is  virtually  non-poisonous. 

Formaldehyde  is  readily  absorbed  and  held  in  solution 
by  water  to  the  extexnt  of  40  per  cent,  by  weight  of  the 
latter,  but  as  soon  as  this  proportion  is  exceeded  there  is  a 
polymerization  of  the  gas  and  a  solid  (paraformaldehyde 
or  paraform)  is  precipitated,  which  is  only  resolved  again 
into  formaldehyde  at  a  temperature  of  275°  F.  The  40 
per  cent,  solution  is  practically  identical  with  the  prepa- 
ration which  is  commercially  known  as  formalin,  and 
has  usually  an  addition  of  10  per  cent,  of  methyl  alcohol 
to  further  guard  against  precipitation.  Very  weak  solu- 
tions (1  or  2  per  cent.)  of  the  gas  are  still  effectively  dis- 
infectant, while  its  virtue  as  an  antiseptic  persists  even 
when  the  dilution  is  carried  to  a  remarkable  degree. 

One  peculiar  effect  of  the  solutions  is  that  of  rendering 
connective  tissue  and  all  gelatinous  substances  insoluble 
in  either  hot  or  cold  water,  and  it  is  probably  to  this  that 
its  germicidal  activity  is  largely  due,  since  the  food  supply 
of  the  bacteria,  if  not  the  substance  of  the  latter  them- 
selves, is  partly  of  this  nature.  For  the  same  reason  it 
hardens  and  disagreeably  roughens  the  skin,  which  tends 
to  prevent  its  use  for  topical  applications. 

Several  methods  have  been  devised  for  the  production 
or  liberation  of  formaldehyde  in  rooms  and  buildings  in 
such  volume  as  positively  to  secure  both  surface  and  pene- 
trative disinfection.  Of  these,  the  best  results  seem  to 
have  been  obtained  where  a  solution  of  the  gas,  such  as 


DISINFECTION  AND  QUARANTINE.  277 

formalin,  is  heated  and  vaporized.  For  instance,  in  Tril- 
lat's  apparatus  the  solution  is  heated,  calcium  chloride 
also  being  added  to  further  insure  against  the  precipitation 
of  paraform.  A  simpler  device,  called  a  regenerator, 
allows  the  solution  to  flow  in  a  fine  stream  through  a 
copper  coil  heated  to  redness  by  a  flame  beneath,  the  gas 
and  vapor  then  passing  directly  into  the  room  in  a  super- 
heated and  effective  condition.  Both  of  these  methods 
have  the  advantage  that  the  apparatus  may  be  operated 

*  FIG.  37.  FIG.  38. 


Trillat's  autoclave  or  apparatus  for  Regenerator  for  vaporizing  for- 

liberating  formaldehyde.  maldehyde  solutions. 

outside  of  the  room  to  be  disinfected,  and  the  action  ac- 
cordingly controlled;  also  that  the  amount  of  gas  liberated 
depends  directly  upon  the  strength  and  quantity  of  the 
solution  evaporated. 

In  the  Schering  method,  the  solid  paraform  is  heated  in 
a  receptacle  over  an  alcohol  lamp,  the  volume  of  resulting 
formaldehyde  depending,  of  course,  upon  the  amount  of 
paraform  used.  This  method  has  yielded  some  excellent 
results  experimentally,  and  is  of  special  value  in  disinfect- 


278 


MANUAL  OF  HYGIENE  AND  SANITATION. 


ing  small  rooms,  closets,  and  sterilizing  cases  made  for 
instruments,  dressings,  etc. 

Probably  the  cheapest  and  most  common  form  of  appa- 
ratus is  that  which  has  been  devised,  in  the  form  of  a 
portable  lamp,  to  develop  the  gas  directly  by  the  oxidation 
of  methyl  alcohol,  the  vapors  of  the  latter  being  made  to 
pass  over  or  through  tubes  or  coils  of  heated  metal,  and  to 
be  thus  converted  into  the  disinfectant  gas.  Considerable 
formaldehyde  can  doubtless  be  produced  in  this  way,  but 


FIG.  39. 


FIG.  40. 


Schering's  lamps  for  volatilizing  parafonn. 

the  amount  at  any  time  is  uncertain  and  the  results  indefi- 
nite, since  part  of  the  alcohol  vapors  are  polymerized  and 
part  are  further  oxidized  into  compounds  such  as  carbon 
monoxide  and  carbon  dioxide.  Therefore  this  method  is 
only  to  be  advised  for  comparatively  small  apartments  or 
enclosures,  and  not  where  certainty  of  disinfection  is 
important. 

Whenever  formaldehyde  is  employed  as  a  gas  all  the 
apertures  in  the  room  should  be  carefully  and  tightly 
closed,  since,  having  the  same  specific,  gravity  as  the  air, 
its  diffusion  takes  place  rapidly.  Moreover,  after  a  suffi- 


DISINFECTION  AND  QUARANTINE. 


279 


cient  volume  of  the  gas  has  been  liberated,  it  should  be 
allowed  to  act  as  long  as  possible,  preferably  for  twenty- 
four  hours  at  least,  since  the  time  element  is  just  as  impor- 
tant a  factor  with  this  as  with  other  disinfectants. 

Lastly,  the  gas  is  an  excellent  deodorant,  combining  as 
it  does  with  the  effluvia  from  decomposing  substances  to 
produce  odorless  compounds.  Its  odor,  in  turn,  may  be 
quickly  dissipated  from  a  room  by  evaporating  a  little 
ammonia  therein. 

The  following  table  of  Koch  and  Jaeger  is  added  to 
show  the  comparative  disinfectant  strength  of  some  sub- 
stances occasionally  used  for  the  purpose: 


Disinfectant. 


Bichloride  of  mercury 


Silver  nitrate  .    .    .    . 


Acid,  hydrochloric  .    .     2 

{2 
15 

Ferrum  chlorate  ...  5 
Calcium  chloride  .  .  5 
Potass,  permanganate  5 

Caustic  Ume     .    .  {«™l 


Strength. 

1  to  20,000 

1  to    1,000 

1  to  12,000 

1  to    4,000 

1  to    2,500 

2  to       100 


100 
100 
100 
100 
100 
100 
100 


Acid,  carbolic 


Formaldehyde 
(K.  Walter). 


to    1,000 


10  to       100 


1  to 
3  to 


100 
100 


Objects  submitted          Time  required 

to  experiments.          for  destruction. 

Anthrax  spores.  10  minutes. 

Anthrax  spores. 

Anthrax  spores. 

Cholera  and  typhoid 

Diphtheria. 

Anthrax  spores. 

Anthrax  spores. 

Anthrax  spores. 

Anthrax  spores. 

Anthrax  spores. 

Anthrax  spores. 

Cholera. 

Typhoid. 

Staphylococcus  and 
streptococcus  pyog. 

Anthrax  spores. 
/Nearly  all  patho- 
\    genie  germs. 

Anthrax  spores 

All  other  patho- 
genic germs 


1  minute. 
70  hours. 

2  hours. 
2  hours. 

10  days. 
53  days. 

8  days. 

6  days. 

5  days. 
Iday. 

6  hours. 
6  hours. 

}  &-11  seconds. 

24  hours, 
f  Less  than 
1 30  minutes. 

15  minutes. 

|  1  minute 


In  any  case  of  infectious  disease  special  attention  should 
be  given  to  disinfecting  the  excretions  and  secretions  which 
are  known  to  be  most  likely  to  contain  the  disease  germs, 


280    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

viz.,  the  desquamating  epithelium  in  measles  and  scarlet 
fever,  and  likewise  the  renal  secretion  in  the  latter;  the 
dejecta  in  typhoid  fever;  the  sputum  and  possibly  the 
dejecta  in  tuberculosis;  secretions  from  the  throat  in 
diphtheria,  etc. 

During  the  course  of  the  illness  there  should  be  no 
more  communication  than  is  absolutely  necessary  between 
the  occupants  of  the  sick-room  and  those  in  the  rest  of  the 
house,  and  a  sheet  should  be  hung  at  the  door  and  kept 
moist  with  some  disinfecting  solution,  as  this  will  largely 
prevent  the  escape  of  infected  dust  particles  through  the 
doorway.  All  articles  going  from  the  room,  whether 
dishes,  clothing,  or  food,  should  be  submerged  in  a  disin- 
fectant or  covered  with  a  cloth  wet  with  it,  and  should  be 
burned,  boiled,  or  otherwise  disinfected  as  soon  as  possible 
thereafter.  Excreta  should  be  disinfected  as  soon  as  dis- 
charged from  the  body,  but  should  not  be  emptied  into  a 
water-closet,  sewer,  or  cesspool  till  the  disinfectant  has 
had  ample  time  to  do  its  work.  Ventilation  should  be  as 
perfect  as  possible;  sunlight  should  be  admitted  whenever 
it  will  not  injure  or  annoy  the  patient,  and,  above  all,  clean- 
liness in  every  respect  should  be  insisted  upon  as  being 
most  essential. 

It  is  taken  for  granted  that,  if  possible,  before  the  occu- 
pancy of  the  room  by  the  sick,  all  upholstered  furniture, 
heavy  drapery,  and  everything  not  absolutely  necessary 
were  removed  from  the  room.  Even  the  carpet  should  be 
taken  up  and  rugs  used  temporarily  in  its  place.  If  this 
is  done,  the  work  of  disinfecting  the  room  after  it  is  no 
longer  needed  by  the  patient  will  be  greatly  facilitated. 

Where  the  use  of  formaldehyde  is  not  available,  the  final 
disinfection  should  be  carried  out  as  follows :  All  bed- 
clothing,  etc.,  should  be  either  submerged  in  some  disin- 


DISINFECTION  AND  QUARANTINE.  281 

fectant  solution  or  in  boiling  water,  or  else  covered  with  a 
sheet  wet  with  a  disinfectant,  and  boiled  as  soon  as  possible 
thereafter.  No  clothing  should  be  sent  away  from  the 
house  to  be  laundered.  Bedquilts,  blankets,  mattresses, 
etc.  should  be  subjected  to  steam  sterilization  if  possible; 
if  not,  the  blankets  and  quilts  should  be  carefully  sterilized 
by  boiling,  and  the  mattresses  would  better  be  burned.  The 
carpet  or  rugs  should  be  carefully  taken  up,  carried  to  an 
open  space,  well  beaten,  and  then  hung  in  the  open  air  for 
a  time,  provided  they  cannot  be  sent  at  once  to  some 
place  where  steam  sterilization  is  available.  All  furni- 
ture and  the  woodwork  of  the  room  should  be  washed 
with  corrosive  sublimate  solution  (1  to  500  or  1000),  tak- 
ing care  to  get  the  fluid  into  all  crevices.  The  floor 
may  be  scrubbed  with  lye,  and  then  mopped  and  flooded 
with  a  corrosive  sublimate  solution.  The  walls  should 
also  be  wiped  with  cloths  wrung  out  of  this  solution  and  any 
paper  upon  them  removed  before  fumigaton,  unless  it  be 
new  and  free  from  cracks.  Or  the  walls  may  be  rubbed 
down  with  the  crumb  of  bread  and  the  latter  burned,  as  the 
bread  contains  much  gluten,  to  which  the  dust  and  bacteria 
adhere.  Fumigation  will  scarcely  be  necessary,  and  is 
usually  of  somewhat  doubtful  efficiency.  If  it  is  employed, 
all  openings  from  the  room,  cracks,  crevices,  etc.,  should  be 
closed  on  the  outside,  and  sufficient  gas  (chlorine  or  sul- 
phurous acid)  liberated  by  suitable  means.  The  vessels 
containing  the  gas-generating  substances  should  be  placed 
in  larger  vessels  containing  water  to  avoid  the  danger  of 
fire,  and  vapor  of  water  should  be  liberated  in  some  way 
simultaneously  with  the  gas,  say  by  placing  hot  bricks  or 
the  like  in  the  water,  as  neither  chlorine  nor  sulphurous 
acid  has  much  disinfecting  value  except  in  the  presence  of 
moisture.  The  room  should  then  remain  closed  for  twenty- 


282    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

four   hours  and,  lastly,  should  be  well  ventilated  for  a 
day  or  two  before  being  furnished  and  occupied  again. 

Should  it  be  possible  to  use  formaldehyde,  the  disin- 
fection is  much  simplified,  for  comparatively  few  articles 
need  be  removed  from  the  room,  while  the  remainder  will 
probably  be  thoroughly  sterilized  by  the  proper  use  of  a 
sufficient  quantity  of  the  gas,  say  that  liberated  from  one 
pint  of  a  40  per  cent,  solution  for  each  1000  cubic  feet  of 
space. 

Quarantine. 

Quarantine  may  be  described  as  the  methods  and  meas- 
ures imposed  by  a  government — local,  State,  or  national — 
to  prevent  the  introduction  of  infectious  disease  into  the 
country  or  from  one  locality  to  another.  Although  the 
term  in  itself  is  misleading,  being  derived  from  the  Italian 
"  quarante,"  and  signifying  the  period  of  detention  of  the 
first  Venetian  quarantines,  it  is  now  generally  taken  to 
indicate  the  entire  routine  of  inspection,  disinfection,  and 
detention,  without  regard  to  the  length  of  time  involved. 

While  all  civilized  nations  have  from  the  earliest  times 
recognized  the  importance  of  separating  those  afflicted  with 
epidemic  disease  from  the  well,  the  development  of  the 
idea  and  practice  of  quarantine  has  necessarily  been  con- 
sequent upon  the  growth  of  commerce;  and  while  there 
had  practically  always  been  isolation  for  leprosy,  the  first 
quarantine  enactments,  in  our  meaning  of  the  term,  were 
put  in  force  in  Venice  about  the  beginning  of  the  fifteenth 
century  as  a  barrier  to  both  the  black  and  the  Egyptian 
plague.  Then  it  was  realized  that  epidemic  diseases  were 
transmitted  by  those  attacked,  a  bureau  of  health  and  a  laz- 
aretto were  established,  the  effects  of  those  who  died  of  the 
plague  were  destroyed,  and  the  period  of  detention  of  incom- 
ing vessels,  passengers,  and  cargoes  was  fixed  at  forty  days. 


DISINFECTION  AND  QUARANTINE.  283 

As  time  went  on  and  the  plague  spread  over  the  whole 
of  Europe,  the  number  of  lazarettos  was  largely  increased, 
especially  in  the  eighteenth  century.  Of  these,  the  one 
at  Marseilles  became  the  most  noted,  not  only  because  it 
was  located  at  one  of  the  most  important  ports  of  the 
Mediterranean,  but  because  of  its  excellent  care  and  man- 
agement. Thanks  to  the  increased  efficacy  of  quarantine 
and  other  sanitary  regulations,  as  the  knowledge  concern- 
ing them  developed,  the  plague  rapidly  subsided  soon  after 
the  beginning  of  the  present  century,  and  interest  in  it 
was  supplanted  by  that  in  relation  to  the  frequent  epi- 
demics of  cholera  and  yellow  fever  that  began  to  alarm 
the  civilized  world,  and  it  is  to  prevent  the  ingress  of 
these  latter  diseases,  together  with  small-pox  and.  typhus 
fever,  that  the  present  quarantine  regulations  are  in  the 
main  devised. 

With  the  knowledge  already  gained  regarding  the 
nature  and  causes  of  infectious  diseases,  their  periods  of 
incubation,  etc.,  it  is  at  once  evident  that  it  will  be  neither 
necessary  nor  wise  to  fix  upon  a  prolonged  and  arbitrary 
time  during  which  vessels  or  passengers  must  be  detained 
in  quarantine.  All  that  is  needed  is  that  the  proper  inspect- 
ing officers  shall  be  satisfied  that  there  is  no  danger  of 
contagion  entering  the  country,  and  where  any  detention 
is  necessary  it  is  only  for  so  long  as  will  suffice  for  the 
disinfection  of  the  vessel,  cargo,  and  passengers'  effects, 
and  to  cover  the  period  of  incubation  of  the  suspected 
disease. 

The  present  quarantine  laws  of  the  United  States,  and 
the  latest  regulations  of  the  Treasury  Department  based 
upon  them,  are  especially  designed  to  afford  the  greatest 
possible  protection  to  the  country  against  the  importation 
of  disease  with  the  least  possible  detention  of  incoming 


284    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

vessels  and  passengers.  An  important  innovation  that 
facilitates  both  these  ends  has  been  the  establishment  of 
quarantine  in  foreign  lands,  as  it  were,  viz.,  the  inspection 
and,  if  necessary,  disinfection  by  officers  of  this  govern- 
ment of  all  vessels,  passengers,  and  cargoes  leaving  a 
foreign  port  for  any  port  of  the  United  States.  This 
undoubtedly  greatly  diminishes  the  danger  of  the  intro- 
duction of  any  contagious  disease;  but,  in  addition,  there 
is  that  section  of  the  law  that  provides  that  the  President 
may,  whenever  the  condition  of  affairs  shall  seem  to  war- 
rant it,  "  prohibit,  in  whole  or  in  part,  the  introduction  of 
persons  and  property  from  such  countries  or  places  as  he 
shall  designate  and  for  such  period  of  time  as  he  shall 
deem  necessary." 

Accordingly,  every  vessel  clearing  from  a  foreign  port 
for  this  country  must  obtain  from  the  United  States  con- 
sular officer  of  the  port,  or  from  the  medical  officer  ap- 
pointed for  the  purpose,  a  bill  of  health,  "  setting  forth 
the  sanitary  history  and  condition  of  said  vessel,  and  that 
it  has  in  all  respects  complied  with  the  rules  and  regu- 
lations in  such  cases  prescribed  for  securing  the  best 
sanitary  condition  of  the  said  vessel,  its  cargo,  passen- 
gers, and  crew."  Before  signing  the  bill  of  health  the 
consular  or  medical  officer  must  be  satisfied  that  the 
conditions  certified  to  therein  are  true,  and  must  per- 
sonally inspect  "  all  vessels  from  ports  at  which  cholera 
prevails,  or  at  which  yellow  fever,  smallpox,  or  typhus 
fever  prevails  in  epidemic  form,"  and  "  all  vessels  carry- 
ing steerage  passengers."  Moreover,  the  vessel  must  be 
clean  in  all  parts  before  taking  on  either  passengers  or 
crew,  and  all  parts  liable  to  infection  must  be  disinfected, 
if  any  infectious  disease  has  occurred  on  the  last  voyage. 
The  bedding  provided  for  steerage  passengers  must  also 


DISINFECTION  AND  QUARANTINE.  285 

be  destroyed  or  else  disinfected  before  being  used  on 
another  voyage. 

The  regulations  also  indicate  what  kinds  of  cargo,  com- 
ing from  or  through  infected  districts,  may  or  may  not  be 
shipped,  and  what  kinds  must  invariably  be  disinfected 
under  any  circumstances. 

As  to  the  passengers,  while  they  are  divided  into  two 
classes,  cabin  and  steerage,  no  person  suffering  from 
cholera,  smallpox,  yellow  or  typhoid  fever,  scarlet  fever, 
measles,  or  diphtheria  is  allowed  to  ship;  nor  should  pas- 
sengers ship  from  an  infected  port.  Steerage  passengers 
and  crew  who  have  been  exposed  to  smallpox  must  be 
vaccinated  before  shipping  unless  they  can  show  proof  of 
immunity  by  former  attack  or  satisfactory  vaccination.  If 
the  steerage  passengers  and  crew  have  been  exposed  to 
typhus-fever  infection  they  may  not  embark  until  fourteen 
days  after  such  exposure  and  the  disinfection  of  their  bag- 
gage, while  steerage  passengers  from  cholera-infected  dis- 
tricts must  be  detained  in  suitable  quarters  for  five  days, 
' '  the  said  period  to  begin  only  after  the  bathing  of  the 
passengers,  disinfection  of  all  their  baggage  and  apparel, 
removal  of  all  food  brought  with  them,  and  isolation  from 
others  not  so  treated."  The  same  rules  as  to  detention 
and  disinfection  are  to  be  applied  to  those  coming  from 
places  where  the  plague,  yellow  fever,  or  smallpox  is  prev- 
alent in  an  epidemic  form,  and  if  one  of  these  diseases  or 
cholera  breaks  out  in  the  detention  barracks  there  must  be 
a  repetition  of  the  five  days'  isolation,  disinfection,  etc., 
dating  from  the  removal  of  the  last  case.  Cabin  passengers 
from  cholera  or  other  infected  ports  or  districts  should  pro- 
duce satisfactory  evidence  as  to  their  place  of  abode  for  the 
five  days  immediately  preceding  embarkation,  and  if  there 
is  any  reason  for  the  belief  that  any  one  of  these  or  his 


286    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

baggage  has  been  infected,  such  passenger  is  to  be  detained 
as  long  as  the  inspecting  officer  may  deem  wise,  and  his  bag- 
gage is  to  be  disinfected. 

Every  passenger  must  also  have  an  inspection-card, 
stamped  by  the  consular  or  medical  officer,  giving  name 
of  passenger,  and  of  ship,  port,  and  date  of  departure,  etc. : 
and  all  baggage  of  passengers  must  have  a  label  bearing 
the  seal  or  stamp  of  the  United  States  consular  or  medical 
officer,  the  name  of  port  and  of  the  vessel  carrying  the 
baggage,  and  the  statement  and  date  of  inspection  or 
disinfection. 

It  is  evident  that  if  these  regulations  at  foreign  ports, 
together  with  those  required  at  sea — viz.,  rigorous  clean- 
liness and  free  ventilation  of  the  vessel,  daily  inspection 
by  the  ship's  physician,  isolation  and  disinfection  of  the 
sick,  etc. — be  properly  observed,  there  can  be  but  little 
chance  of  the  germs  of  quarantinable  disease  gaining 
entrance  to  our  country,  and,  since  the  duration  of  the 
voyage  will  in  most  cases  exceed  the  period  of  incubation 
of  most  of  the  contagious  diseases,  if  none  of  these  mani- 
fest themselves  on  shipboard  at  sea  there  will  be  no  need 
for  any  detention  at  the  port  of  entry  beyond  that  which 
the  inspecting  officer  stationed  there  requires  for  the  per- 
formance of  his  duties,  viz.,  to  inspect  the  vessel,  bill  of 
health,  crew,  and  passengers,  and  their  lists  and  manifests, 
ship  physician's  clinical  record  of  all  cases  treated,  and, 
when  necessary,  the  ship's  log. 

This  inspection  service  is  to  be  maintained  at  every  port 
throughout  the  year,  and  is  in  force  not  only  with  respect 
to  all  vessels  from  foreign  ports,  but  regarding  any  vessel 
with  sickness  on  board,  vessels  from  domestic  ports  where 
cholera  or  yellow  fever  prevails,  or  where  smallpox  or 
typhus  fever  prevails  in  epidemic  form,  vessels  from  for- 


DISINFECTION  AND  QUARANTINE.  287 

eign  ports  carrying  passengers  having  entered  a  port  of 
the  United  States  without  complete  discharge  of  passen- 
gers or  cargo,  and  vessels  having  been  treated  at  national 
quarantine  stations  that  are  located  a  considerable  distance 
from  the  port  of  entry  of  said  vessels.  Moreover,  the 
duties  of  the  inspecting  officer  above  stated  are  only  the 
required  minimum  standard,  and  such  other  regulations 
may  be  added  by  legal  State  or  local  authorities  as  may, 
for  special  reasons,  be  necessary. 

If  the  inspecting  or  health  officer  is  satisfied  that  the 
vessel  is  not  infected,  and  all  the  foregoing  requirements 
have  been  complied  with,  he  gives  his  certificate,  to  be 
delivered  to  the  collector  of  customs  of  the  port,  and  no 
vessel  is  permitted  to  land  any  of  its  passengers  or  cargo 
unless  it  have  this  certificate,  together  with  the  bill  of 
health,  etc.,  from  the  port  of  departure,  as  evidence  that 
the  regulations  have  been  properly  observed.  On  the 
other  hand,  if  vessels  arrive  under  the  following  condi- 
tions they  are  to  be  remanded  by  the  authority  of  the 
Secretary  of  the  Treasury  to  the  nearest  national  or  other 
quarantine  station,  where  proper  accommodations  and  ap- 
pliances are  provided  for  the  necessary  disinfection  and 
treatment  of  the  vessel,  passengers,  and  cargo;  and  only 
after  treatment  and  after  obtaining  a  certificate  from  the 
proper  officer  that  the  vessel,  cargo,  and  passengers  are 
each  and  all  free  from  infectious  disease,  or  from  danger 
of  conveying  the  same,  can  a  vessel  be  admitted  to  entry 
to  the  ports  named  in  the  certificate. 

The  conditions  under  which  arriving  vessels  are  to  be 
placed  in  quarantine  are  these  :  "A.  With  quarantine  dis- 
ease on  board,  the  quarantinable  disease  for  the  purposes 
of  these  regulations  being  cholera  (cholerine),  yellow  fever, 
smallpox,  typhus  fever,  and  leprosy.  B.  Having  had 


288    A  MANUAL  OF  HYGIENE  AND  SANITATION, 

such  on  board  during  the  voyage  or  within  thirty  days 
next  preceding  arrival;  or,  if  arriving  in  the  quarantine 
season,  having  had  yellow  fever  on  board  after  March  1st 
of  the  current  year,  unless  satisfactorily  disinfected  there- 
after. C.  From  ports  infected  with  cholera  or  where  typhus 
fever  prevails  in  epidemic  form,  coming  directly  or  via 
another  foreign  port,  or  via  United  States  ports,  unless 
they  have  complied  with  the  United  States  quarantine 
regulations  for  foreign  ports;  also  vessels  from  non-infected 
ports,  but  bringing  persons  or  cargo  from  places  infected 
with  cholera,  yellow  fever,  or  where  typhus  fever  prevails 
in  epidemic  form,  except  as  subsequently  noted.  D.  From 
ports  where  yellow  fever  prevails,  unless  disinfected  in 
accordance  with  these  regulations,  and  not  less  than  five 
days  have  elapsed  since  such  disinfection. 

"  The  following  exceptions  may  be  made  to  Rules  C. 
and  D.  with  regard  to  vessels  quarantined  against  on 
account  of  yellow  fever :  (1)  Vessels  arriving  from 
November  1st  to  May  1st  may  be  admitted  to  entry. 
(2)  Vessels  bound  for  ports  in  the  United  States  north  of 
the  southern  boundary  of  Maryland,  with  good  sanitary 
condition  and  history,  having  had  no  sickness  on  board  at 
ports  of  departure,  en  route  or  on  arrival,  provided  they 
have  been  five  days  from  last  infected  or  suspected  port, 
may  be  allowed  entry  at  port  of  destination.  But  if  said 
vessels  carry  passengers  destined  for  places  south  of  this 
latitude  the  baggage  of  said  passengers  shall  be  disin- 
fected, and  such  baggage  shall  be  labelled.  (3)  Vessels 
engaged  in  the  fruit  trade  from  ports  declared  safe  for  this 
purpose  by  the  Supervising  Surgeon-General  of  the  Marine 
Hospital  Service  may  be  admitted  to  entry  without  deten- 
tion, provided  they  carry  no  passengers  and  have  carried 
no  passengers  from  one  port  to  another,  and  have  no 


DISINFECTION  AND  QUARANTINE.  289 

household  effects  or  personal  baggage  in  cargo,  and  have 
complied  with  the  rules  and  regulations  made  by  the  Sec- 
retary of  the  Treasury  with  regard  to  vessels  engaged  in 
said  trade."1 

Moreover,  all  passengers  other  than  those  occupying 
first  or  second  cabin,  and  all  persons  arriving  on  vessels 
that  have  had  smallpox  on  board,  must  be  vaccinated  or 
detained  in  quarantine  not  less  than  fourteen  days,  unless 
they  can  show  satisfactory  evidence  of  recent  vaccination 
or  of  having  had  smallpox;  and  all  effects  and  compart- 
ments liable  to  convey  infection  must  be  disinfected. 

"  No  case  of  leprosy  will  be  landed,  and  vessels  arriving 
at  quarantine  with  leprosy  on  board  shall  not  be  granted 
pratique  until  the  leper  with  his  or  her  baggage  has  been 
removed  from  the  vessel  to  the  quarantine  station.  If 
the  leper  is  an  alien  passenger  and  from  a  foreign  port, 
action  will  be  taken  as  provided  by  the  immigration  laws 
and  regulations  of  the  United  States.  If  the  leper  is  an 
alien  and  a  member  of  the  crew,  and  the  vessel  is  from  a 
foreign  port,  said  leper  shall  be  detained  at  quarantine  at 
the  vessel's  expense,  until  taken  aboard  by  the  same  vessel 
when  outward  bound. "2 

There  are  ten  national  quarantine  stations  and  a  number 
of  others  under  State  or  municipal  control;  those  which 
have  steam  disinfection  chambers  and  other  efficient  equip- 
ments are  located  at  Portland,  Me. ;  Boston,  New  York, 
Sandy  Hook,  Delaware  Breakwater,  Reedy  Island  in  the 
Delaware  River,  Cape  Charles,  Baltimore;  Wilmington, 
N.C. ;  Savannah,  Blackbeard  Island, Ga. ;  Charleston,  Dry 
Tortugas,  Key  West,  Mullet  Keys,  Pensacola,  Mobile, 
Chandeleur  Islands,  New  Orleans,  Galveston,  San  Diego, 

i  Quarantine  Laws  and  Regulations  of  the  United  States.  2  Ibid, 

19 


290    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

San  Francisco,  and  Port  Townsend;  the  ten  national  ones 
being  included  in  the  list. 

The  essential  requisites  for  a  properly  equipped  quaran- 
tine station,  after  the  selection  of  a  proper  location — which 
should  be  convenient,  but  not  in  the  line  of  future  city 
growth — are  the  following:1  1.  A  boarding  station,  includ- 
ing boat-house  and  boatmen's  quarters.  2.  A  boarding- 
boat,  preferably  a  steamer.  3.  An  anchorage  for  the  de- 
tention of  infected  vessels.  It  should  be  safely  out  of  the 
track  of  commerce,  convenient  but  not  too  close  to  the 
main  quarantine  establishment,  sheltered,  and  with  good 
holding  ground  for  anchors.  4.  A  fumigation  steamer 
with  appliances  for  generating  and  forcing  sulphurous- 
acid  (or  formaldehyde}  gas  into  vessels,  and  with  tanks 
and  pumps  for  disinfecting  solutions.  5.  A  wharf,  in 
water  at  least  twenty  feet  deep,  and  upon  which  are  con- 
structed a  warehouse,  tanks  for  disinfecting  solutions,  and 
a  disinfecting  house  containing  steam  disinfecting  cham- 
bers. 6.  A  lazaretto  or  hospital  for  the  treatment  of 
contagious  diseases.  7.  A  hospital  for  non-contagious  dis- 
eases. 8.  Barracks  or  quarters  for  the  detention  in  groups 
of  those  who  may  have  been  exposed  to  contagion  or 
infection.  9.  Quarters  for  medical  officers.  10.  A  cre- 
mation furnace. 

When  a  vessel  is  remanded  to  quarantine  by  the  inspect- 
ing officer  at  a  port  of  entry,  its  treatment  and  that  of  its 
cargo  and  passengers  will  depend  largely  upon  the  disease 
with  which  it  is  infected,  being  more  severe  if  the  latter 
is  cholera  or  yellow  fever.  In  case  of  infection  by  either 
of  these  diseases,  the  vessel  is  at  once  sent  to  the  anchorage, 
and  must  remain  there  until  the  passengers  have  been  dis- 

i  RohS's  Hygiene. 


DISINFECTION  AND  QUARANTINE.  291 

charged  and  the  vessel  purified,  and  in  any  case  there  must 
be  no  direct  communication  allowed  between  quarantine, 
or  a  vessel  in  quarantine,  and  any  person  or  place  outside. 

Moreover,  if  cholera  has  occurred  on  board,  all  passen- 
gers and  all  of  the  crew,  except  such  as  are  necessary  to 
care  for  her,  must  be  at  once  removed,  the  sick  to  be  sent 
to  the  lazaretto  or  hospital,  others  specially  suspected  must 
be  carefully  isolated,  and  the  remainder  separated  into 
small  groups,  between  which  there  must  be  no  communi- 
cation. Those  who  are  especially  liable  to  convey  infec- 
tion must  be  bathed  and  furnished  with  sterile  clothing 
before  entering  the  barracks,  and  no  articles  capable  of 
carrying  infective  matter,  especially  food,  should  be  taken 
into  the  barracks.  If  the  disease  has  occurred  in  the 
steerage,  all  the  steerage  passengers  must  be  bathed  and 
their  clothing  disinfected;  and  in  any  case  all  steerage 
baggage  and  effects,  and  any  other  baggage,  etc. ,  that  has 
been  exposed  to  the  infection,  all  articles  of  the  cargo 
likely  to  be  infected,  and  all  living  apartments,  furniture, 
and  such  other  portions  of  the  vessel  as  may  possibly 
retain  or  convey  infection  must  be  disinfected.  The  water- 
supply  must  be  changed  at  once,  the  tanks  thoroughly  dis- 
infected by  steam  or  permanganate  of  potash  solution,  and 
refilled  with  water  from  a  pure  source  or  with  water 
recently  boiled.  The  water-ballast  of  a  cholera-infected 
vessel,  or  of  one  from  a  cholera-infected  port,  should 
never  be  discharged  in  fresh  or  brackish  water  without 
previous  disinfection,  and  the  ballast-tanks  should  be  re- 
filled with  sea- water  or  else  be  disinfected  before  refilling. 
Nothing  is  to  be  thrown  overboard  from  a  cholera-infected 
vessel  in  quarantine,  but  everything  that  is  to  be  destroyed, 
even  deck-sweepings,  should  be  burned  in  the  furnace. 

The  disinfection  of  the  holds  of  vessels  is  to  be  by 


292    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

mechanical  cleansing,  by  an  acid  bichloride  of  mercury 
solution  (1  to  800)  applied  under  pressure,  and  by  sul- 
phurous-acid gas  (10  per  cent,  volume  strength)  for  from 
twenty-four  to  forty-eight  hours.  All  ballast  must  be 
discharged  or  disinfected  before  the  disinfection  of  the 
hold,  and  all  solid .  ballast  must  be  disinfected  before 
being  discharged  into  fresh  water.  The  steerage  and  fore- 
castle are  to  be  disinfected  by  live  steam,  if  possible,  for 
at  least  half  an  hour,  and,  if  not,  by  sulphur  dioxide  and 
bichloride  solution,  as  was  the  hold.  Baggage,  bedding, 
carpets,  etc.,  are  to  be  removed  with  caution  and  to  be 
disinfected  by  steam  or  by  boiling,  and,  finally,  all  wood- 
work of  the  vessel  is  to  be  thoroughly  cleansed  mechani- 
cally and  then  washed  with  an  acid  bichloride  of  mercury 
solution  (1  to  1000). 

Under  date  of  August  5,  1897,  the  Secretary  of  the 
Treasury  issued  a  circular  to  State  and  local  quarantine 
authorities  t(  amending  Article  5  of  the  quarantine  regu- 
lations to  be  observed  at  ports  and  on  the  frontiers  of  the 
United  States,  by  adding  two  paragraphs,  8  and  9. 

"Disinfection  of  steerage,  forecastle,  and  cabin  of  vessels  by 
formaldehyde  gas.  After  the  removal  of  the  bedding,  car- 
pets, and  furnishings,  all  apertures  being  tightly  closed, 
the  steerage,  forecastle,  and  cabin  of  a  vessel  may  be  dis- 
infected by  formaldehyde  gas  in  a  percentage  of  not  less 
than  2  per  cent,  per  volume  strength,  the  time  of  exposure 
to  be  not  less  than  twelve  hours.  The  gas  may  be  gen- 
erated by  the  following  method  : 

"From  an  aqueous  solution,  containing  40  per  cent,  of 
the  gas,  known  under  the  names  of  formaldehyde,  formol, 
or  formolose.  The  gas  is  best  evolved  from  these  solutions 
by  the  addition  of  from  10  to  30  per  cent,  of  a  neutral 
salt,  preferably  calcium  chloride  or  sodium  nitrate,  and 


DISINFECTION  AND  QUARANTINE.  293 

heating  the  mixture  in  a  special  boiler.  One  litre  of  a  40 
per  cent,  solution  of  formaldehyde  gas  will  evolve  about 
1425  litres  (50.1  cubic  feet)  of  the  gas  at  20°  C.  (68°  F.), 
and  will  be  sufficient  for  17  cubic  metres  (2505.5  cubic 
feet)  of  space. 

" After  the  disinfection  of  apartments  by  formaldehyde 
gas,  the  latter  should  be  neutralized  by  ammonia  gas, 
evolved  from  water  of  ammonia  by  heat,  or  by  evapora- 
tion from  water  of  ammonia  sprinkled  upon  the  floor. 
The  quantity  of  water  of  ammonia  required  for  neutrali- 
zation, after  the  above-named  method,  is  as  follows :  1 J 
litres  (1.26  quarts)  of  water  of  ammonia  for  each  litre 
(1.01  quarts)  of  formaldehyde  solution. 

"Disinfection  of  clothing,  bedding,  upholstered  furniture, 
articles  of  leather,  etc. ,  by  formaldehyde  gas.  These  may 
be  disinfected  by  formaldehyde  gas  in  the  ordinary  steam 
disinfecting  chamber,  the  latter  to  be  provided  with  a 
vacuum  apparatus  and  special  apparatus  for  generating 
and  applying  the  gas.  The  gas  should  be  applied  in  a 
dry  state  in  not  less  than  20  per  cent,  per  volume  strength, 
the  time  of  exposure  to  be  not  less  than  one  hour. 

"The  application  of  the  disinfectant  can,  of  course,  be 
modified  to  suit  the  circumstances  of  the  case,  but  the  fore- 
going will  be  useful  as  indicating  the  principles  which 
must  be  followed." 

As  to  the  passengers  and  others  who  have  been  isolated 
in  groups,  they  are  to  be  inspected  twice  daily  by  the  physi- 
cian and  remain  under  his  constant  surveillance,  and  can 
have  no  communication  with  any  one  in  a  different  group 
or  outside  of  quarantine,  except  through  the  quarantine 
officer.  The  water-  and  food-supply  is  to  be  strictly 
guarded,  and  is  issued  to  each  group  separately.  The 
latter  is  to  be  simple  in  character  and  abundant  in  quan- 


294    ^  MANUAL  OF  HYGIENE  AND  SANITATION. 

tity,  but  no  fruit  is  to  be  permitted.  Strict  cleanliness  is 
to  be  enjoined,  disinfection  wherever  necessary,  and,  in 
case  cholera  appears  in  any  group,  the  sick  will  be  imme- 
diately removed  to  the  hospital,  and  the  rest  of  the  group 
bathed  and  their  effects  disinfected,  and  all  then  removed 
to  other  quarters,  if  possible.  None  are  to  leave  quaran- 
tine until  five  days  after  the  last  exposure  to  infection  and 
the  final  disinfection  of  such  effects  as  were  taken  to  bar- 
racks; and  no  convalescent  may  leave  quarantine  until  a 
bacteriological  examination  shows  him  to  be  free  from 
infection. 

As  has  been  stated,  the  treatment  of  vessels  infected  by 
other  diseases  is  not  necessarily  so  severe  as  the  above,  but 
in  each  case  every  effort  is  made  to  allow  no  loophole  for 
the  entrance  of  infection  into  the  country;  and  in  the  case 
of  yellow  fever  there  is  to  be  the  same  isolation  of  all  not 
required  to  care  for  the  vessel  and  a  detention  of  at  least 
five  days  after  disinfection  has  been  thoroughly  performed 
and  completed.  The  detention  for  typhus  fever  is  to  be 
twenty  days,  and  for  smallpox  fourteen  days,  the  detention 
dating  from  the  last  exposure  to  either  disease. 

No  vessel  may  leave  quarantine  until  she  has  a  certifi- 
cate from  the  health  (quarantine)  officer  that  she  has  in  all 
respects  complied  with  the  quarantine  regulations,  and 
that,  in  his  opinion,  she  will  not  convey  quarantinable 
disease.  She  is  then  said  to  be  granted  free  pratique. 

The  law  farther  provides  that  "  When  practicable,  alien 
immigrants  arriving  at  Canadian  and  Mexican  ports,  des- 
tined for  the  United  States,  shall  be  inspected  at  the  port 
of  arrival  by  the  United  States  consular  or  medical  officer, 
and  be  subjected  to  the  same  sanitary  restrictions  as  are 
called  for  by  the  rules  and  regulations  governing  United 
States  ports;  that  inspection  cards  will  be  issued  by  the 


DISINFECTION  AND  QUARANTINE.  295 

United  States  officer  at  the  port  of  arrival  to  all  such 
immigrants,  and  labels  affixed  to  their  baggage,  as  in  the 
case  of  foreign  ports;  and  where  such  immigrants  are  not 
inspected  at  the  port  of  arrival  they  shall  enter  the  United 
States  only  at  certain  designated  points  on  the  frontier, 
and  then  only  after  such  inspection,  detention,  disinfec- 
tion, vaccination,  etc.  as  may  be  necessary  or  required  by 
the  officers  there  stationed. 

There  is  also  provision  for  the  inspection  of  State  or 
local  quarantines  from  time  to  time  by  the  Supervising 
Surgeon-General  of  the  Marine-Hospital  Service,  or  by 
an  officer  of  that  service  detailed  by  him;  and  for  the 
observance  at  all  quarantines  of  such  additional  rules  and 
regulations  as  may  from  time  to  time  be  promulgated  by 
him. 

Inland  Quarantine.  Under  this  heading  may  be  con- 
sidered the  means  that  may  be  employed  to  prevent  an 
epidemic  extending  from  one  locality  or  district  to  another, 
although  the  principle  and  aims  are  practically  the  same 
as  those  of  maritime  quarantines,  viz.,  to  define  certain 
boundaries  beyond  which  no  person  or  thing  capable  of 
carrying  infection  may  pass,  and  to  establish  certain 
points  of  ingress  or  egress  on  these  boundaries  where 
there  may  be  the  necessary  detention,  inspection,  disinfec- 
tion, etc. 

The  sanitary  cordon  "  consists  of  a  line  of  guards,  mili- 
tary or  civil,  thrown  around  a  district  or  locality,  either 
to  protect  the  same  from  the  surrounding  country  when 
infected,  or  to  protect  the  surrounding  country  from  the 
infected  district  or  locality."  "It  is  not  intended  to 
bottle  up  all  the  people  who  are  caught  within  an  infected 
district,  but,  on  the  contrary,  is  intended  as  a  means  of 
exit  to  those  who  will  not  carry  with  them  contagious  dis- 


296    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

eases  to  the  people  beyond.m  It  may  be  single  or  double; 
in  the  latter  case  the  inner  line  closely  encircles  the  well- 
defined  infected  locality,  and  the  outer  line  the  whole  sus- 
pected territory.  This  latter  may  be  removed  as  soon  as 
it  is  evident  that  the  space  between  it  and  the  inner  line  is 
not  infected.  To  be  efficient  the  cordon  must  be  so  guarded 
that,  even  though  it  be  many  miles  in  length,  no  unauthor- 
ized person  may  pass  through  it,  while  at  certain  places 
upon  it  camps  of  probation  or  detention  must  be  estab- 
lished, where  all  persons  coming  from  the  infected  locality 
may  be  kept  under  observation  for  a  time  equal  to  the 
period  of  incubation  of  the  disease  in  question.  These 
camps  of  probation  or  detention  are  to  be  distinguished 
from  the  camps  of  refuge,  which  were  first  suggested  by 
Surgeon-General  Woodward  in  1878,  and  which  are 
"  simple  residence-camps  established  to  receive  the  popu- 
lation of  an  infected  community  when  it  has  been  deter- 
mined to  depopulate  the  infected  district.77 

At  these  camps  of  probation  provision  must  be  made 
for  inspecting  every  person  and  disinfecting  all  baggage 
before  entering  camp,  for  isolating  the  occupants  and 
housing  and  feeding  them  in  the  most  comfortable  and 
sanitary  manner  during  the  detention,  for  inspections 
twice  or  thrice  daily,  for  the  isolation  and  care  of  the  sick 
in  hospitals  at  a  safe  distance  from  camp,  and  for  the  issu- 
ance of  a  certificate  granting  "  f ree  pratique"  when  the 
period  of  detention  is  over. 

A  notable  instance  of  the  sanitary  cordon  was  that  about 
the  city  of  Brownsville,  Texas,  and  along  the  Rio  Grande, 
in  1882;  and  of  a  probation  camp,  that  at  Camp  Perry, 
Florida,  in  1888. 

*  RohS's  Hygiene :  Quarantine. 


DISINFECTION  AND  QUARANTINE.  297 

In  addition  to  these  measures  it  may  be  necessary  or 
advisable  to  establish  a  railroad  quarantine,  as  follows:  At 
certain  convenient  points,  which  will  be  the  only  points 
of  egress  by  rail  from  the  infected  district,  an  inspec- 
tion service  and  disinfecting  station  are  to  be  maintained 
throughout  the  epidemic.  Here  all  the  baggage  and 
freight  is  to  be  properly  disinfected  and  all  passengers 
are  to  be  examined  by  the  official  inspectors;  if  the  latter 
are  from  the  infected  locality,  or  have  not  a  certificate  from 
some  recognized  health  officer  as  to  where  they  have  been 
for  the  previous  days  corresponding  to  the  incubative 
period  of  the  disease,  they  are  to  be  at  once  remanded  to 
the  nearest  camp  of  probation,  there  to  undergo  the  neces- 
sary detention.  Moreover,  it  may  seem  advisable  to  pre- 
vent any  passenger  cars  going  beyond  the  infected  district, 
and  to  disinfect  all  freight  and  baggage  cars  that  do  so.1 

1  In  the  foregoing  chapter  the  author  has  attempted  to  present  briefly  the  prin- 
ciples and  the  regulations  of  quarantine  as  practised  in  the  United  States  at  the 
present  time ;  but  the  reader  is  referred  for  further  details  to  the  extremely  inter- 
esting and  valuable  chapter  on  the  subject  in  Rohe's  "  Text-Book  of  Hygiene," 
by  Dr.  Wyman,  the  present  Supervising  Surgeon-General  of  the  Marine-Hospital 
Service. 


•CHAPTEK    XI. 

THE   REMOVAL   AND    DISPOSAL   OF   SEWAGE. 

THE  waste  from  dwellings  is  of  three  kinds :  house- 
sweepings  and  the  ashes  from  fires;  the  waste  from  kitch- 
ens, scraps  of  food,  etc.,  commonly  known  as  garbage; 
and  sewage,  the  most  important,  consisting  as  it  does  of 
the  solid  and  liquid  excreta  of  the  body,  together  with 
waste  water  from  wash-tubs,  bath-tubs,  kitchens,  laun- 
dries, etc. 

Ashes  alone  have  little  effect  upon  the  health,  except 
that  they  absorb  moisture  readily,  and  if  allowed  to  accu- 
mulate in  a  cellar  may  do  much  to  keep  it  damp  and 
mouldy.  For  the  same  reason,  if  they  be  mixed  with 
refuse  vegetable  matters,  putrefaction  is  favored  and  nox- 
ious emanations  given  off.  The  dust  from  ash  heaps  may 
also  be  carried  into  the  house  and  largely  increase  the  solid 
impurities  of  the  air  therein.  Consequently,  ashes  should 
be  frequently  and  regularly  removed  from  the  premises. 

Kitchen  garbage  readily  decays,  and  if  allowed  to  re- 
main in  the  vicinity  of  the  house  may  pollute  both  the  air 
and  soil  about  it;  but  inasmuch  as  it  has  some  value  as  a 
food  for  animals,  there  is  usually  no  difficulty  in  having 
it  removed  by  scavengers  without  expense  or  delay.  Care 
must  be  had,  however,  that  this  is  done  properly,  and  that 
all  receptacles  are  kept  in  as  cleanly  a  condition  as  possi- 
ble. Most  large  cities  now  find  it  safer  to  collect  and 
cremate  the  garbage  at  the  expense  of  the  municipality, 
rather  than  to  allow  private  individuals  to  keep  large 


THE  REMOVAL  AND  DISPOSAL  OF  SEWAGE.     299 

numbers  of  animals  within  or  near  the  city  limits  for  its 
consumption.  Even  though  the  former  plan  be  the  more 
costly,  experience  shows  that  this  garbage  may  be  com- 
pletely consumed  in  properly  arranged  crematories  at  con- 
venient localities  without  inconvenience  or  annoyance  to 
the  residents  of  the  vicinity,  thus  saving  the  expense  and 
time  necessary  for  conveying  the  garbage  beyond  the 
municipal  limits. 

The  kind  of  waste  to  which  we  give  the  name  of  sewage 
is,  however,  of  most  importance  to  sanitarians,  since  it  is 
always  a  possible  factor  in  the  production  of  disease,  and 
since  it  presents  the  most  difficulties  in  respect  to  its  re- 
moval from  dwellings  and  the  ultimate  disposal  of  it. 

In  addition  to  the  substances  already  named,  and  which 
usually  come  from  dwelling-houses,  sewage  may  contain 
the  liquid  excreta  from  stables,  the  refuse  from  factories 
of  all  kinds,  the  drainage  from  polluted  soils,  and  the 
excess  of  rain-water  not  taken  up  by  evaporation  or 
retained  in  the  soil.  Its  composition  must,  therefore,  be 
always  complex  and  variable ;  but  there  will  practically 
always  be  present  in  it  chloride  of  sodium,  ammonia,  car- 
bon monoxide  and  dioxide,  hydrogen  and  ammonium  sul- 
phide, fetid  and  decomposing  organic  matter,  and  myriads 
of  bacteria.  Fresh  sewage  will  not  be  as  offensive  to  the 
senses  as  that  in  which  putrefaction  has  commenced,  nor 
will  the  gases  arising  from  it  be  as  dangerous  to  health. 
Frankland  has  shown  that  "  solid  or  liquid  matter  is 
not  likely  to  be  scattered  into  the  air  from  the  sewage 
itself  by  any  agitation  it  is  likely  to  undergo  until  gas 
begins  to  be  generated  in  it;"  and  it  is  really  doubtful 
whether  the  air  of  a  properly  constructed  and  well-venti- 
lated sewer  can  be  shown  to  contain  a  harmful  excess  of 
injurious  gases  and  organisms.  However,  it  is  essential 


300    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

that  sewage  should  always  be  removed  from  the  premises 
of  a  dwelling  as  soon  as  possible  after  its  production  and 
before  decomposition  begins. 

When  the  above-mentioned  constituents  of  sewage  are 
to  be  disposed  of  collectively,  the  water-carriage  system  is 
usually  the  best.  Although  the  pneumatic  system  (wherein 
air-tight  pipes  extend  from  the  dwellings,  etc.,  to  reser- 
voirs from  which  the  air  is  periodically  exhausted  and  the 
sewage  thus  drawn  into  them),  would  seem  to  be  advan- 
tageous where  the  topographical  conditions  do  not  permit 
of  natural  drainage,  it  is  always  subject  to  the  danger  of 
breaks  occurring  and  destroying  the  action,  and  seems  to 
have  been  practically  successful  in  but  very  few  instances. 

On  the  other  hand,  where  house  refuse  only  is  to  be 
considered  and  where  the  waste  water  can  be  kept  from 
the  other  parts  of  the  sewage,  or  where  the  water-supply, 
the  physical  conditions,  or  the  cost  of  constructing  the 
necessary  sewers  prevent  the  use  of  the  water-carriage 
method,  recourse  must  be  had  to  the  pail  or  earth-closet 
system.  The  use  of  primitive  privy-vaults  or  cesspools  is 
most  insanitary  and  dangerous,  and  should  be  condemned 
in  almost  every  instance.  Where  the  necessity  for  one  of 
these  seems  imperative,  it  should  always  be  made  abso- 
lutely water-tight,  so  that  none  of  the  contents  may  escape 
to  pollute  the  surrounding  soil  and  soil-air  and  to  contam- 
inate the  ground-water  in  the  neighborhood.  Moreover, 
the  pits  should  be  properly  ventilated  and  should  be 
cleaned  out  regularly  and  often,  which  may  be  done  satis- 
factorily and  without  offence  by  some  form  of  odorless 
excavating  apparatus,  such  as  is  now  commonly  used. 
No  drains  or  sewers  should  empty  directly  into  a  cess- 
pool, but  these  should  always  be  trapped  and  have  com- 
munication with  the  open  air,  and  no  cesspool  should 


THE  REMOVAL  AND  DISPOSAL  OF  SEWAGE.     3Q1 

empty  into  a  common  or  public  sewer.  It  should  be 
noted  that  the  contents  of  such  a  vault,  or  of  a  simple  pit  in 
the  earth,  undergo  putrefaction  rather  than  natural  decom- 
position, because  of  the  lack  of  sufficient  oxygen  supply 
and  of  the  adjunct  action  of  the  nitrifying  bacteria  which 
are  found  only  in  the  uppermost  layers  of  the  soil.  It  is 
also  probable  that  many  disease  germs  will  survive  and 
multiply  better  in  the  contents  of  such  a  vault  than  in 
sewage  or  refuse  treated  by  the  methods  to  be  hereafter 
described. 

In  the  pail  system  the  more  solid  waste  matters,  and 
especially  human  excreta,  are  collected  in  a  suitable  pail 
or  tub,  which,  holding  only  a  limited  amount,  must  of 
necessity  be  removed  and  emptied  regularly  and  often.  If 
the  outbuildings  used  for  this  purpose  be  kept  clean  and 
properly  ventilated,  such  a  system  will  be  both  economical 
and  healthful. 

Advantage  may  here  be  taken  of  the  great  deodorizing, 
nitrifying,  and  oxidizing  power  of  fine  dry  earth,  and 
various  forms  of  earth-closets  have  been  devised  to  be  used 
in  conjunction  with  the  pail-system.  If  a  quantity  of  dry 
earth,  in  bulk  about  twice  that  of  the  dejecta,  is  thrown 
upon  the  latter  after  using  the  closet,  they  will  be  rendered 
perfectly  inodorous  and  inoffensive.  For  this  purpose 
loam  and  clay  are  best,  though  sifted  ashes  may  be  used 
with  almost  as  good  results,  but  sand  or  gravel  will  not 
be  so  efficient  as  the  loam  or  ashes.  Moreover,  owing 
probably  to  the  action  of  the  nitrifying  bacteria  in  the 
earth,  all  trace  of  the  peculiar  nature  of  the  organic  com- 
pound is  quickly  destroyed,  and  the  mixture  soon  be- 
comes practically  humus  and  an  excellent  fertilizer. 

The  pail  or  earth-closet  must,  of  course,  be  separate  and 
apart  from  the  dwelling,  as  it  is  impossible  to  have  the 


302    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

same  means  of  keeping  the  gaseous  emanations  and  effluvia 
out  of  the  house  as  with  the  water-carriage  system;  and 
it  also  goes  without  saying,  that  the  liquid  house-slops, 
wash-water,  etc.,  must  be  kept  separate  from  the  fecal 
waste,  which  should  be  kept  as  dry  as  possible  to  lessen 
putrefaction  and  to  increase  its  possible  value  as  a  fertil- 
izer. Nor  should  this  liquid  waste  be  allowed  to  soak 
into  and  pollute  the  soil  about  the  house.  It  should  be 
collected  in  a  water-tight  reservoir,  whence  it  can  be 
removed  at  frequent  intervals,  or,  better  yet,  carried  by 
suitable  drains  to  a  kitchen  garden  or  other  land  at  a 
proper  distance  from  the  house,  and  be  there  disposed  of 
by  irrigation  or  sub-irrigation. 

As  one  can  readily  see,  this  pail  system  is  especially 
well  adapted  to  isolated  houses  and  small  communities, 
where  each  householder  can  take  care  that  the  necessary 
details  are  properly  attended  to,  and  where,  as  is  likely, 
there  is  not  a  general  water-supply,  or  where  the  expense  of 
constructing  the  necessary  sewers  would  be  too  great.  But 
even  in  cities  as  large  as  Manchester,  England,  "  where 
four-fifths  of  the  people  are  obliged  to  have  earth-closets/7 
the  system  is  said  to  have  proved  entirely  advantageous 
and  practicable. 

Where  there  is  a  common  and  general  supply  of  water 
throughout  the  house  or  to  a  number  of  houses  there 
must  be  some  provision  for  carrying  off  the  waste  water, 
and  as  this  latter  will  have  probably  become  polluted  in 
its  use,  it  will  be  advantageous  to  utilize  it  to  remove  the 
other  sewage.  In  fact,  where  the  conditions  are  favorable 
the  water-carriage  system  will  usually  be  found  the  best 
of  all,  because  it  is  more  nearly  automatic,  and  depends 
least  on  human  interference  and  efficiency. 

The  necessary  apparatus  comprises,  on  the  one  hand, 


THE  REMOVAL  AND  DISPOSAL  OF  SEWAGE.     303 

that  which  belongs  to  the  building  and  its  premises,  viz., 
the  house  fixtures,  pipes,  and  drains;  and,  on  the  other 
hand,  the  common  or  public  sewers  which  receive  the  sew- 
age from  the  above  and  convey  it  to  its  place  of  ultimate 
disposal. 

Sewage-plumbing  and  House-drainage. 

The  essence  of  any  good  system  for  the  removal  of  sew- 
age from  a  dwelling  or  building  is  simplicity.  Therefore, 
inasmuch  as  it  has  already  been  stated  that  sewage  should 
always  be  removed  from  the  premises  as  soon  as  possible 
after  its  production  and  before  fermentation  or  putrefac- 
tion begin  in  it,  it  is  evident  that  in  such  a  system  we 
should  have  for  our  object  and  should  provide  for  :  "  1. 
The  speediest  possible  removal  from  the  house  to  the 
public  sewer  of  excretal  and  other  refuse  by  means  of 
water.  2.  The  prevention  of  the  deposit  of  foul  matter 
in  any  part  of  the  drainage  system  and  of  percolation 
into  the  soil  of  polluting  liquids.  3.  The  establishment  of 
a  current  of  air  through  every  part  of  the  soil-drains  and 
pipes,  in  order  to  disperse  any  foul  gases  that  may  form 
and  to  allow  them  to  escape  with  safety  into  the  open  air. 
4.  The  prevention  of  any  entry  of  air  from  soil-pipes, 
drains,  and  waste-pipes  into  the  house.  5.  The  exclusion 
of  the  air  of  the  common  sewer  from  the  house-drains  and 
the  house;  the  last  being,  perhaps,  the  most  important,  as 
the  air  of  the  public  sewer  may  at  any  time  contain  the 
active  germs  of  specific  disease/71 

This  is  to  be  done  in  the  manner  to  be  described.  The 
soil-pipe  is  that  which  receives  the  sewage  from  water- 
closets  and,  usually,  from  the  waste-pipes  of  other  fixtures, 

i  L.  C.  Parkes :  Hygiene  and  Public  Health,  2d  edition,  p.  139, 


304    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

such  as  the  bath-tubs,  washstands,  sinks,  etc.,  and  which 
connects  them  with  the  house-drain;  the  latter  is  the  con- 
duit connecting  the  soil-pipe  with  the  sewer.  Waste-pipes 
convey  the  contents  of  washstands  and  other  fixtures  to 
the  soil-pipes  or  to  a  branch  of  the  house-drain. 

The  soil-pipe  is  usually  located  almost  entirely  within 
the  house,  although,  were  it  not  for  the  danger  of  its  con- 
tents freezing,  it  would  be  better  to  have  it  fastened  to  the 
wall  outside.  It  is  usually  made  of  cast  or  wrought  iron, 
should  be  at  least  four  inches  in  diameter,  should  convey 
the  sewage  as  directly  as  possible  from  the  fixtures  to  the 
house-drain,  and  must  extend  unobstructed  from  the  latter 
to  several  feet  above  the  roof,  ending  where  winds  and 
currents  from  high  walls  and  chimneys  will  not  interfere 
with  its  free  ventilation.  Every  branch  of  the  soil-pipe 
more  than  eight  feet  in  length,  or  to  which  two  or  more 
water-closets  are  connected,  should  also  be  extended  above 
the  roof,  or  else  be  extended  and  connected  to  the  main 
soil-pipe  above  the  highest  fixture  connected  therewith,  as 
there  must  be  no  closed  ends  wherein  foul  or  stagnant  air 
may  collect.  All  joints  must  be  absolutely  air-tight,  and 
the  pipe  must  be  so  secured  that  any  vibration  or  settling 
of  the  building  will  not  be  likely  to  destroy  its  continuity. 
In  new  buildings,  especially,  all  soil-pipes  should  be  ex- 
posed or  else  covered  in  with  panels  easily  removable  at 
any  time  to  permit  of  inspection  or  repairs.  Any  hidden 
pipes  or  those  difficult  of  access  should  be  of  extra  heavy 
materials,  and  extra  care  should  be  given  to  the  joints  and 
supports.  The  soil-pipe  and  house-drain  should  both  be 
as  smooth  as  possible  interiorly,  and  in  the  construction 
they  must  be  carefully  inspected  to  prevent  any  of  the 
material  used  in  daulking  or  cementing  the  joints  from 
projecting  within  to  prevent  the  free  flow  of  sewage. 


THE  REMOVAL  AND  DISPOSAL  OF  SEWAGE.    305 


Outside  of  the  house  the  house-drain  may  be  of  iron  or 
of  glazed  and  impervious  earthenware,  but  no  earthen  pipe 


FIG.  41. 


WASH  BASIN 


WASH  BASIN 


V 


BATH-TUB/ 


Diagram  illustrating  the  sewage-plumbing  of  a  house.  The  traps  of  the  rain- 
leaders  at  their  junctions  with  the  house-drain,  and  the  name  of  the  latter,  have 
been  accidentally  omitted. 

should  be  permitted  within  five  feet  of  a  foundation  wall, 
and  where  any  part  of  the  house-drain  is  within  the  build- 

20 


306 


MANUAL  OF  HYGIENE  AND  SANITATION. 


ing  it  should  be  of  iron  and  securely  fastened  to  the 
foundation-  wall  above  the  cellar  floor.  The  connection 
between  it  and  any  soil-pipe  should  be  by  means  of  a 
rounded  elbow  and  not  by  an  abrupt  right  angle.  The 
house-drain  should  not  be  less  than  four  nor  more  than 
ten  inches  in  diameter,  should  be  laid  on  a  firm  founda- 
tion, should  have  air-tight  joints,  and  should  have  a  slope 
toward  the  sewer  of  at  least  one-half  inch  to  the  foot. 
A  house-drain  should  not  empty  into  a  cesspool,  unless  it 
is  absolutely  necessary,  and  in  such  case  the  cesspool  must 
be  well  ventilated  and  also  separated  from  the  drain  by 
a  trap.  Nor  should  any  cesspool  empty  into  a  sewer. 

PIG.  42. 


Method  of  connecting  soil-pipe  with  house-drain. 

If  a  house-drain  empty  into  a  sewer  of  the  ' '  combined ' ' 
system  there  must  be  a  trap  just  before  its  junction  with 
the  sewer  to  prevent  the  passage  of  sewer-air  back  into 
the  house,  and  there  must  also  be  an  opening  for  fresh  air 
between  this  trap  and  the  foot  of  the  soil-pipe,  so  that 
there  may  be  a  constant  current  of  air  through  the  drain 


THE  REMOVAL  AND  DISPOSAL  OF  SEWAGE.     307 

and  soil-pipe  to  the  exit  above  the  roof,  and  the  air  in  the 
soil-pipe  thus  kept  from  becoming  foul  and  stagnant.  But 
if  the  house-drain  empties  into  a  sewer  of  the  "  separate  " 
system,  there  need  be  no  trap  between  the  drain  and 
sewer,  for  the  reasons  to  be  hereafter  stated;  however,  the 
fresh-air  inlet  between  sewer  and  soil-pipe  is  always 
advisable,  as  it  tends  to  further  assist  ventilation. 

Where  rain-water  conductors  empty  into  house-drains 
or  sewers,  they  should  be  separated  from  the  latter  by 
traps  having  a  seal  of  not  less  than  five  inches,  to  prevent 
sewer-air  passing  up  through  them  to  the  vicinity  of  win- 
dows, etc. 

In  the  house  all  water-closets  and  other  fixtures  should 
be  as  near  the  soil-pipe  as  possible,  that  there  may  be  no 
long  stretches  of  foul  waste  pipe  underneath  the  floors, 
and  all  connections  with  the  soil-pipe  should  be  made  at 
an  acute  angle,  that  the  discharge  into  the  latter  may  not 
interfere  with  its  free  ventilation.  Each  fixture  must  be 
separately  trapped  and  the  trap  must  be  located  as  near 
its  fixture  as  possible.  There  must  be  no  connection  be- 
tween a  fixture  and  the  soil-pipe  or  house-drain  which  is 
not  trapped. 

A  little  reflection  will  show  that  provision  has  been 
made  for  each  of  the  five  specified  requisitions  for  the 
system,  and  that  if  the  foregoing  specifications  are  observed, 
the  air  in  the  soil-pipes  will  be  almost  as  pure  as  that  of 
the  house  itself,  and  the  absorption  of  foul  gases  by  the 
water  in  the  house-traps  and  their  subsequent  dispersion 
into  the  atmosphere  of  the  house  will  be  almost  impossible. 
But  there  must  always  be  both  an  inlet  and  an  outlet  for 
air  to  the  house-drain  and  soil-pipe,  and  free  communica- 
tion between  these;  otherwise  the  air  in  the  soil-pipe  can- 
not be  changed,  and  foul  gases  will  accumulate,  which  by 


308    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

their  pressure  might  overcome  the  seal  of  some  of  the 
traps. 

Traps  are  "  appliances  placed  between  house  conven- 
iences (fixtures)  and  soil-pipes  and  drains  or  sewers,  to 

FIG.  43.  FIG.  44. 


These  illustrations  show  how  a  uniform  calibre  prevents  the  accumulation  of 
dirt  in  a  trap,  and  how  angles  and  corners  favor  such  accumulations. 

prevent  sewer-gas  gaining  an  entrance  into  the  house." 
Most  traps  are  too  complicated.  The  simpler  a  trap 
the  better,  provided  it  have  sufficient  seal.  Mechanical 
appliances  are  liable  to  become  clogged  and  not  to  fit 

FIG.  45. 


S,  or  siphon,  trap,  with  opening  for  ventilation  pipe. 

tightly,  thus  allowing  the  passage  of  sewer-air.  The  S, 
or  siphon,  trap  is  as  simple  as  any,  is  of  uniform  diameter 
throughout,  has  no  corners  or  projections  to  catch  dirt,  and 


THE  REMOVAL  AND  DISPOSAL  OF  SEWAGE.     309 


is  thoroughly  cleansed  by  each  fair  flow  of  water  through 
it.  The  value  of  a  trap  does  not  depend  so  much  on  the 
amount  of  water  it  contains  as  on  the  depth  of  the  seal. 
On  account  of  evaporation  the  water-seal  of  a  trap  soon 


FIG.  46. 


FIG.  47. 


Bell  trap. 


CudelPs  trap. 


becomes  lessened  or  destroyed,  unless  its  fixture  be  in  fre- 
quent use;  it  is,  therefore,  advisable  to  have  as  few  fixtures 
of  any  kind  in  the  house  as  the  comfort  or  convenience  of 
the  inmates  will  allow.  So,  also,  if  a  house  is  to  be  left 


FIG.  48. 


FIG.  49. 


Bower's  trap. 


Pot  trap  (for  kitchen  sinks,  etc.). 


unoccupied  for  a  time,  it  is  well  to  cover  the  water  in  the 
traps  with  oil  or  glycerin  to  prevent  the  evaporation  of 
the  former. 


310 


MANUAL  OF  HYGIENE  AND  SANITATION. 


The  seal  of  a  trap  may  be  broken  by  siphonage,  either 
by  a  rush  of  water  through  it  from  its  own  fixture,  or  by 
a  rush  down  the  soil-pipe  from  a  fixture  higher  up,  and 
this  is  especially  liable  to  occur  if  the  trap  be  some  dis- 
tance from  the  soil-pipe,  or  if  the  fixtures  above  discharge 
a  large  amount  of  water  at  once.  To  prevent  this  open- 
ings are  sometimes  made  at  the  top  of  the  traps  on  the 

FIG.  50. 


McClellan's  anti  siphon  attachment.  Sectional  view  of  vent,  with  cup  lifted 
out  of  the  mercury  by  the  inflowing  current -of  air,  indicated  by  the  arrows- 
(ROH£.) 

side  next  the  waste-  or  soil-pipe  and  connected  with  vent- 
pipes,  which  should  open  into  the  soil-pipe  above  the 
entrance  of  the  waste-pipe  from  the  highest  fixture,  or  into 
a  separate  ventilation-pipe.  But  this  greatly  increases  the 
expense,  and  as  the  vent-pipes,  to  be  efficient,  must  be 
almost  two  inches  in  diameter,  they  also  favor  evaporation 
from  the  trap.  If  the  trap  is  properly  constructed,  the 


THE  REMOVAL  AND  DISPOSAL  OF  SEWAGE.     3H 

soil-pipe  of  proper  size  and  height,  and  if  the  fixtures  be 
placed  as  near  the  soil-pipe  as  possible,  there  will  be  but 
little  danger  of  siphonage  occurring.  Where  it  does  occur, 
McClellan's  anti-siphon  attachment  is  said  to  work  advan- 
tageously, being  inexpensive  and  permitting  a  free  ingress 
of  air  to  the  trap,  but  no  egress  of  air  from  the  soil-pipe 
into  the  house.  It  is  also  said  that  if  the  fixture  be 
connected  to  the  soil-pipe  by  a  divergent  opening,  siphon- 
age  will  be  less  likely  to  occur. 

All  waste-pipes,  soil-pipes,  and  house-drains  should  be 
tested  before  use  by  closing  all  openings  and  forcing  in  air 
to  a  pressure  of  at  least  thrity  pounds  to  the  square  inch. 
Leaks  may  be  detected  by  plugging  the  lower  openings 
and  filling  the  pipes  with  water,  or  by  pouring  an  ounce 
of  oil  of  peppermint  into  the  highest  fixture  and  quickly 
following  this  with  several  gallons  of  hot  water,  the  heat 
volatilizing  the  oil,  whose  odor  escapes  at  every  opening 
in  the  pipes  unprotected  by  a  trap  or  water-seal.  The 
heat  imparted  by  the  hot  water  will  also  help  to  trace  out 
hidden  soil-pipes. 

All  fixtures  should  be  exposed  to  the  free  ventilation  of 
air  underneath  and  about  them,  and  water-closets  and 
washstands  should  not  be  closed  in  with  carpentry  work. 
Traps  should  also,  if  possible,  be  where  they  may  be 
opened  and  inspected  at  any  time.  Under  each  fixture 
there  should  be  a  drip-safe  to  catch  any  leakage  or 
overflow  of  water,  but  the  pipes,  if  there  be  any,  leading 
from  these  should  never  empty  into  waste-  or  soil-pipes; 
they  should  lead  preferably  to  the  open  air,  and  not  to 
the  cellar,  as  the  air  in  most  cellars  is  bad,  and  thus  gains 
access  to  the  house.  Even  if  these  drip-safe  pipes  are 
trapped  and  open  into  the  soil-pipe,  the  water  in  the  trap 
is  replenished  so  rarely  that  evaporation  soon  destroys  the 


312    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

seal  and  allows  the  air  to  pass  from  the  soil-pipe  into  the 
house. 


8 


The  overflow  pipe  of   old-fashioned  wash  stands   and 
bath-tubs  is  objectionable,  as  it  collects  dirt  of  all  kinds, 


THE  REMOVAL  AND  DISPOSAL  OF  SEWAGE.    313 

soap,  epithelium,  etc.,  and  it  is  almost  impossible  to  clean 
it.  Besides,  it  will  often  be  found  opening  into  the  waste- 
pipe  below  the  trap,  thus  allowing  the  free  passage  of  sewer- 
air  into  the  room.  When  new  fixtures  are  being  put  in 
they  should,  preferably,  be  such  as  make  use  of  the  stand- 
pipe  principle  in  the  stoppers,  and  that  have  no  separate 
or  concealed  overflow-pipe  or  outlet. 

Water-closets.     The  requisites  for  a  good  water-closet 
are:    that  it  does  not  allow  the  escape  of  sewer-air  from 

FIG.  52. 


Pan  closet. 

the  soil-pipes  into  the  house;  that  it  is  thoroughly  and 
easily  cleaned  each  time  after  use;  that  there  are  no 
hidden  parts  in  which  filth  can  collect,  or  which  cannot 
be  readily  cleaned;  that  the  flushing  or  washing  out  of  a 
closet  be  done  in  such  a  way  that  dirt  or  spray  be  not 
thrown  into  the  air  of  the  room;  that  there  be  sufficient 
water-supply  to  wash  out  the  bowl  and  trap  each  time,  and 
to  refill  them  to  the  proper  level;  that  the  trap  itself  is 


314    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

not  siphoned  or  left  empty  by  a  discharge  of  water  from 
this  or  another  fixture. 

Of  the  different  kinds  of  water-closets  the  pan  and  the 
valve  closets  are  the  oldest  and  the  worst,  and  should  not 
be  used.  They  consist  of  a  receiving  bowl,  the  bottom  of 
which  opens  into  a  swinging  pan  or  is  closed  by  a  valve. 
The  pan  or  valve  and  the  lower  part  of  the  receiving  bowl 
are  enclosed  in  a  larger  bowl,  the  container,  connected 
with  the  soil-pipe  and  trap.  The  depth  of  water  in  the 

FIG.  53. 


Valve  closet. 

receiving  bowl  is  regulated  by  the  depth  of  the  pan  in 
pan  closets,  and  in  valve  closets  by  the  location  of  an 
overflow  outlet.  In  both  kinds  the  contents  of  the  receiv- 
ing bowl  are  discharged  into  the  container  by  the  tipping 
of  the  pan  or  valve,  and,  consequently,  the  sides  of  the 
container,  as  well  as  the  under  side  of  the  pan  or  valve, 
soon  become  thickly  coated  with  filth.  This,  being 
hidden,  accumulates,  decomposes,  and  contaminates  the 
air  in  the  container,  which  air  is  of  necessity  discharged 


THE  REMOVAL  AND  DISPOSAL  OF  SEWAGE.     315 

into  the  room  as  often  as  it  is  displaced  by  the  contents  of 
the  receiving  bowl.  In  valve  closets  the  overflow-pipe 
from  the  receiver  furnishes  an  additional  way  by  which 
the  foul  air  may  pass  from  the  container  into  the  atmos- 
phere of  the  room.  It  needs  no  argument  to  show  that 
these  closets  are  decidedly  dangerous  to  health. 

Plug  or  plunger  closets  are  those  in  which  the  outlet 
above  the  trap  is  stoppered  by  a  plunger,  this  being 
usually  in  a  chamber  at  the  side  of  the  receiving  bowl. 

FIG.  54. 


Plug  or  plunger  closet. 

The  bowl  and  side  chamber  holding  a  considerable  quan- 
tity of  water,  the  trap  is  well  flushed  out  each  time  of  use; 
but  the  side  chamber  and  plunger,  being  hidden  and  not 
easily  cleaned,  soon  become  coated  with  filth  and  danger- 
ous to  health,  as  there  is  nothing  to  prevent  the  air  from 
passing  from  this  chamber  into  the  room.  Moreover,  the 
plug  may  not  close  the  opening  completely,  thus  allowing 
a  continual  waste  of  water.  A  trapped  overflow-pipe  in 
the  plunger  keeps  the  closet  from  overflowing. 


316     ^  MANUAL  OF  HYGIENE  AND  SANITATION. 

Hopper  closets  consist  simply  of  a  bowl  connected  below 
with  an  ordinary  trap,  and,  as  there  is  nothing  to  get  out 
of  order,  this  kind  is  theoretically  one  of  the  best.  The 
objection  to  long  hoppers  is  that  dirt  is  apt  to  stick  to  the 
sides  and  become  offensive,  but  this  can  be  prevented  if  it 
is  so  arranged  that  water  begins  to  flow  down  the  sides  as 
soon  as  the  closet  is  put  to  use,  thus  preventing  adhesion. 
Short  hoppers  have  not  this  objection,  as  the  feces  fall 
directly  into  the  water  in  the  bowl  and  are  carried  out 

FIG.  55. 


Short-hopper  closet. 

through  the  trap  as  the  bosvl  is  flushed.  All  water-closets 
should  have  a  flushing  rim  encircling  the  top,  so  that  all 
sides  of  the  bowl  may  be  washed  down  and  cleansed  each 
time  the  closet  is  used. 

Wash-out  closets  retain  considerable  water  in  the  bowl, 
and  are  emptied  by  a  strong  flush  of  water  from  the  flush- 
ing rim.  They  are  simple,  do  not  readily  get  out  of  order, 
and  are  much  in  favor  at  the  present  time.  As  they  are 
a  modification  of  the  short-hopper  closet,  so  is  the  siphon 
closet  a  modification  of  the  wash-out. 

In  the  siphon  closets  the  contents  of  the  bowl  and  trap 
are  lifted  out  by  a  siphonic  action,  and  then  the  bowl  and 


THE  REMOVAL  AND  DISPOSAL  OF  SEWAGE.    317. 

trap  are  refilled,  as  in  the  case  of  wash-out  closets,  by  an 
after  flush.  In  the  Dececo  closet — a  siphon  closet — use 
is  made  of  the  principle  involved  in  the  Field  flush  tank. 
Hopper,  wash-out,  and  siphon  closets  should  be  supplied 

FIG.   56. 


Wash-out  water-closet.    (PARKES.) 

from  water-closet  cisterns,  which  should  give  down  a  cer- 
tain and  sufficient  volume  of  water  with  only  a  short  pull 
on  the  chain.  The  bowl  and  trap  should  also  be  refilled 
from  the  cistern  after  use. 

* 

PIG.  57. 


Dececo  siphon  closet.    (PAKKES.) 


Water-closets  should  not  be  connected  directly  to  the 
water-supply  pipes  of  the  house,  as  air  from  the  closets 
may  be  sucked  into  them  at  times  when  the  water-supply 
is  cut  off,  and  the  water  afterward  contaminated  by  it. 


.318 


MANUAL  OF  HYGIENE  AND  SANITATION. 


But  this  is  hard  to  avoid  in  pan,  valve,  or  plug  closets, 
and  is  another  serious  objection  to  their  use. 

Vent-pipes  from  the  bowl  and  seat  of  water-closets  must 
be  large,  and  must  not  open  into  the  soil-pipe  but  into  the 
open  air;  they  must  not  open  near  a  window  nor  any  place 
from  which  air  is  taken  into  the  house,  but  may  open  into 
a  flue  which  is  constantly  heated,  as  a  kitchen  chimney,  or 
may  themselves  be  heated  and  have  a  current  maintained 
in  them  by  a  small  lamp  or  gas-jet.  In  this  way  the 
room  in  which  a  water-closet  is  located  may  be  effectively 
ventilated. 

Water-closets  should  never  be  placed  in  dark  closets, 
nor  in  bedrooms  or  living-rooms,  but  should  always  be  in 
separate  rooms  that  have  free  communication  with  the 
open  air  by  means  of  a  large  window  or  by  a  ventilating 
shaft  of  at  least  four  square  feet  area  throughout  its  entire 
length.  It  is  also  advisable  that  bedrooms  should  not 


FIG.  58. 


Automatic  ejector  for  disinfecting  traps,  water-closets,  etc. 

communicate  directly  with  bath-rooms,  etc.,  containing 
water-closets,  unless  there  is  every  assurance  that  the 
closet  and  plumbing  connected  with  it  are  first  class  in 
every  particular. 


THE  REMOVAL  AND  DISPOSAL  OF  SEWAGE.     319 

A  recent  device  which  is  intended  for  attachment  to  the 
flush-pipes  of  water-closets  and  to  the  waste-pipes  of  other 
fixtures  between  them  and  their  traps,  automatically  dis- 
charges with  each  flow  of  water  through  the  respective 
pipes  a  sufficient  quantity  of  a  disinfectant  to  destroy  and 
prevent  all  growth  of  micro-organisms  in  the  traps  or 
their  contents.  This,  when  used,  will  aid  not  only  in 
preventing  the  escape  of  harmful  or  disagreeable  gases 
into  the  house,  but  will  render  the  addition  of  disease- 
germs  to  the  contents  of  the  public  sewer  almost  impos- 
sible. 

Sewers.  These  are  the  conduits  provided  to  receive 
and  convey  the  contents  of  house-  and  other  drains  to  the 
place  of  final  disposal  or  discharge.  They  may  be  of 
either  of  two  kinds — "combined"  or  "separate"  Sewers 
of  the  former  class,  which  have  heretofore  been  most  com- 
monly used  in  this  country,  are  constructed  to  carry  off 
all  kinds  of  sewage,  the  waste  liquids,  etc.,  from  factories, 
street  washings,  and  the  surplus  rain-water  of  the  district 
drained  by  them.  As  this  necessitates  a  size  and  capacity 
sufficient  to  receive  the  greatest  probable  rainfall  upon  the 
area  drained,  in  addition  to  the  sewage,  it  is  evident  that 
the  depth  of  the  normal  daily  flow  of  the  latter  will  be  so 
shallow  and  the  current  so  sluggish  as  greatly  to  favor  the 
settling  of  the  solid  and  semi-solid  constituents,  the  obstruc- 
tion of  the  sewers,  and  the  development  of  bacteria  and 
sewer-gas.  To  ob.viate  this  and  to  insure  a  more  rapid 
flow  by  keeping  the  depth  of  sewage  as  great  as  possible, 
the  smaller  conduits,  at  least,  are  generally  made  ovoid  in 
section,  the  smaller  end,  of  course,  being  downward. 
"Combined77  sewers  are  not  only  more  expensive  to  con- 
struct and  to  keep  in  repair  than  those  of  the  separate  sys- 
tem, but  greater  care  must  be  had  to  see  that  they  are  at  all 


320    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

times  properly  ventilated.  The  main  advantage  claimed 
for  them  is  that  the  expense  of  constructing  separate  con- 
duits for  factory  wastes,  street  washings,  and  the  excess  of 
rain-water  is  avoided;  but  this  is  a  doubtful  one,  both  in 
respect  to  economy  and  sanitation. 

PIG.  59. 


Section  of  ovoid  sewer  of  "  combined  "  system. 


The  ventilation  of  sewers  of  this  kind  is  usually  suffici- 
ently provided  for  by  the  inlets  for  street  washings  and  rain- 
water, located  at  street  corners,  etc. ;  but  if  these  are  not 
close  enough  together  to  keep  the  sewer  atmosphere  con- 
stantly changing  and  reasonably  pure,  other  ventilation 
openings  must  be  made.  But  in  all  cases  the  air  from  sewers 


THE  REMOVAL  AND  DISPOSAL  OF  SEWAGE.     321 

of  the  combined  system  must  be  excluded  from  house- 
drains,  etc., by  the  traps  which  have  already  been  described. 

To  the  sewers  of  the  "  separate7'  system  only  the  sew- 
age proper  from  dwellings  and,  occasionally,  from  small 
factories,  is  admitted,  the  rain-,  surface-  and  soil-waters 
being  removed  by  other  drains  or  channels.  The  advan- 
tages of  this  system,  which  is  now  indorsed  by  almost  all 
sanitarians,  are  that  the  volume  of  sewage  to  be  carried  is 
comparatively  small  and  constant,  and  that  it  can  be  cal- 
culated very  approximately  from  the  daily  water-supply 
and  population;  that  the  cost  of  construction  is  much  less 
than  that  of  sewers  of  the  combined  system,  and  that, 
while  it  is  perfectly  available  and  satisfactory  for  large 
cities,  it  is  the  only  one  that  small  communities  would 
consider  or  can  afford;  that  the  sewage  is  more  concen- 
trated and  uniform  in  composition,  and  can  thus  be  better 
utilized  as  a  fertilizer  or  disposed  of  in  whatever  manner 
may  be  desirable;  that  the  sewers,  having  smaller  and 
smoother  walls,  are  more  frequently  and  effectually 
flushed,  and  that  they  are  more  completely  ventilated  and 
altogether  better  suited  to  the  work  to  be  performed. 
The  disadvantages  of  sewers  of  this  class  are  that  a  com- 
munity must  have  two  sets  of  drains,  one  for  sewage 
and  the  other  for  rain,  street,  and  factory  waters,  and  that 
after  a  long  dry  season  the  street  washings,  etc.,  may  be 
very  foul;  but  these  are  outweighed  by  the  advantages 
above  mentioned. 

"  No  sewer  of  this  system  should  be  more  than  six 
inches  in  diameter  until  it  and  its  branches  have  accumu- 
lated a  sufficient  flow  at  the  hour  of  greatest  use  to  fill 
this  size  half  full,  because  the  use  of  a  larger  size  is  waste- 
ful and  because  ventilation  becomes  less  complete  as  the 
size  increases.  The  size  should  be  increased  gradually  and 

21 


322    A  MANUAL  OF  HYGIENE  AND  SANITATION. 


only  so  rapidly  as  is  necessary  by  the  filling  of  the  sewer 
half  full  at  the  hour  of  greatest  flow;  and  the  upper  end 
of  eacli  branch  sewer  should  be  provided  with  an  auto- 
matic flush-tank  of  sufficient  capacity  to  secure  the  thor- 
ough daily  cleansing  of  so  much  of  the  conduit  as  from 
the  limited  flow  is  liable  to  deposit  solid  matters  by  the 
way." 

FIG.  60. 


Field's  annular  siphon  flush-tank.    (PARKES.) 

There  should  be  no  traps  between  house-drains  and  sewers 
of  the  separate  system,  since,  having  no  rain-water  inlets, 
the  latter  would  otherwise  have  no  openings  for  ventilation. 
Moreover,  since  the  ' (  separate ' '  sewers  are  so  regularly 
and  thoroughly  flushed,  the  air  in  them  is  not  likely  to  be 
so  impure,  and  there  is  not  the  same  reason  for  excluding 
it  from  the  house-drains,  etc.,  as  there  is  regarding  the 
air  from  "combined"  sewers.  The  junctions  of  house- 
drains  with  sewers  of  the  separate  system  should  be  by 
divergent  openings,  so  that  the  air  may  pass  freely  into 
the  drain  as  the  sewage  empties  into  the  sewer. 

Should  one  desire,  however,  to  separate  his  house-drain 
from  the  public  sewer  by  means  of  a  trap,  and  thus  pre- 


THE  REMOVAL  AND  DISPOSAL  OF  SEWAGE.     323 

vent  the  ingress  of  sewer-air  into  his  premises,  the  venti- 
lation of  the  sewer  can  be  secured  by  providing  a  vent- 
pipe  between  the  trap  and  the  sewer.  But  in  no  case  must 
the  inlet-pipe  on  the  other  side  of  the  trap,  between  it 
and  the  house,  be  omitted;  nor  should  the  two  air-pipes 
be  so  near  together  that  air  from  the  former  will  be  likely 
to  be  drawn  into  the  latter. 

All  sewers  should  be  laid  on  a  good  foundation  with 
sufficient  fall  to  give  at  least  a  velocity  of  two  feet  per 
second  to  the  flow.  If  made  of  bricks  they  should  be 
laid  in  a  mortar  made  of  cement  and  sharp  sand,  and  all 
sewers  should  be  as  smooth  as  possible  inside  to  prevent 
the  arrest  of  particles  of  sewage.  Sewers  of  the  com- 
bined system  should  not  be  pervious  to  the  soil- water,  as 
the  liquid  sewage  is  as  apt  to  pass  from  them  to  the 
soil  and  to  pollute  it  dangerously,  as  the  soil-water  is 
to  pass  into  the  sewers.  But  the  rain-water  drains  of 
the  separate  system  may  also  be  employed  to  drain  the 
subsoil. 

The  ultimate  disposal  of  sewage  is  a  matter  of  con- 
siderable importance  which  commonly  does  not  receive  the 
attention  it  deserves.  The  usual  method  in  this  country 
of  discharging  the  sewage  into  a  running  stream  is  repre- 
hensible, because  the  natural  purification  of  a  water  thus 
contaminated  must  always  be  slow  and  more  or  less  uncer- 
tain, and  because  the  risk  to  those  using  the  polluted  water 
must  be  a  constantly  increasing  one.  Where  the  district 
drained  and  supplied  by  the  stream  is  a  sparsely  settled 
one,  and  where  the  volume  of  fresh  or  running  water  is 
very  large  in  proportion  to  the  quantity  of  pollution  it  re- 
ceives, the  objections  to  the  disposal  of  sewage  in  this  way 
may  be  theoretical  rather  than  practical;  but  as  the  popu- 
lation increases  and  the  ratio  of  pure  water  to  filth  de- 


324    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

creases  beyond  certain  limits,  the  question  becomes  more 
serious  and  pertinent. 

Other  methods  of  sewage  disposal  resemble  closely  those 
already  described  for  the  purification  of  water,  in  that  they 
make  use  of  subsidence,  chemical  treatment,  and  filtration. 
The  sewage  is  collected  in  large  tanks,  with  or  without  the 
addition  of  certain  chemicals,  such  as  lime,  alum,  and  sul- 
phate of  iron,  to  increase  the  precipitation,  and  the  sus- 
pended impurities  are  allowed  to  settle  to  the  bottom  of  the 
tanks,  whence  they  can  be  removed,  squeezed  partially  dry 
in  hydraulic  presses,  and  either  disposed  of  as  a  fertilizer  or 
cremated.  The  clear  effluent  or  liquid  part  of  the  sewage 
may  be  allowed  to  flow  at  once  from  the  settling  tanks  into 
a  convenient  watercourse,  provided  it  is  there  well  diluted, 
or  may  be  filtered  through  an  area  of  porous  soil  or  through 
prepared  filter  beds.  If  the  filtration  is  properly  done  the 
filtrate  will  contain  nothing  harmful,  and  may  be  allowed 
to  flow  where  it  will  without  danger.  A  properly  pre- 
pared filter  bed  of  twelve  inches  of  sand  upon  eighteen 
inches  of  gravel  or  magnetic  carbide  of  iron,  with  an  area 
of  one  acre,  is  said  to  be  able  to  purify  from  one  to  two 
million  gallons  of  clarified — effluent — sewage  in  twenty- 
four  hours. 

Other  ways  in  which  sewage  may  be  disposed  of  are  by 
intermittent  downward  filtration,  by  irrigation,  and  by 
sub-irrigation.  The  soil  to  be  used  for  this  purpose 
should  be  porous  and  loamy;  if  clay,  it  should  be  well 
broken  up  and  mixed  with  ashes;  sand  does  not  do  well, 
especially  at  first  in  these  methods.  The  sewage  impuri- 
ties are  removed  partly  by  mechanical  filtration,  but  espe- 
cially by  oxidation,  the  latter  being  due  partly  to  the  air 
in  the  interstices  of  the  soil,  but  chiefly  to  the  saprophytic 
bacteria,  which  rapidly  convert  the  organic  impurities  into 


THE  REMOVAL  AND  DISPOSAL  OF  SEWAGE.     325 

nitrates  and  nitrites.  In  each  of  these  methods  the  sewage 
should  be  applied  intermittently,  so  that  the  air  in  the  soil 
may  be  periodically  renewed. 

By  intermittent  filtration  we  mean  "  the  concentration 
of  sewage  at  short  intervals,  on  an  area  of  specially  chosen 
porous  ground,  as  small  as  will  absorb  and  cleanse  it;  not 
excluding  vegetation,  but  making  the  produce  of  secondary 
importance.  The  intermittency  of  application  is  a  sine 
qua  non  even  in  suitably  constituted  soils,  wherever  com- 
plete success  is  aimed  at/7  The  land  should  be  levelled 
and  underd rained  with  tile  drains  at  the  depth  of  five 
or  six  feet,  and  should  be  divided  into  four  parts,  no 
part  to  receive  sewage  for  more  than  six  hours.  An 
acre  of  properly  prepared  soil  will  thus  dispose  of  the 
crude  sewage  of  1000,  or  the  clarified  sewage  of  5000 
people. 

Irrigation  means  "the  distribution  of  sewage  over  a 
large  surface  of  ordinary  agricultural  ground,  having  in 
view  a  maximum  growth  of  vegetation,  consistently  with 
due  purification,  for  the  amount  of  sewage  supplied/7 
Sub-irrigation  is  a  modification  of  this,  the  sewage  being 
delivered  through  porous  drains  a  few  inches  beneath  the 
surface  of  the  soil.  Unless  very  porous,  the  land  should 
be  underdrained;  it  should  also  be  levelled  to  prevent  the 
sewage  flowing  off  the  surface  too  rapidly.  The  under- 
drains  need  not  be  nearly  so  close  together,  however,  as  in 
the  intermittent  filtration  system.  The  crops  raised  on 
irrigation  farms  are  perfectly  healthful  in  every  respect, 
and  there  can  be  no  reasonable  objection  to  their  use;  there 
would  be  decided  objection,  however,  to  watering  the 
vegetables  with  sewage  water. 

The  sewage  of  from  one  hundred  to  three  hundred  per- 
sons per  acre  of  irrigation  area  can  be  safely  disposed  of 


326     A  MANUAL  OF  HYGIENE  AND  SANITATION. 

by  this  method,  and  it  is  to  be  especially  recommended  for 
isolated  houses,  for  small  communities,  or  for  charitable  or 
other  State  institutions. 

Electricity  has  also  been  suggested  as  an  agency  for  the 
purification  of  sewage,  but  seems  to  be  still  too  expensive 
for  the  purpose. 


CHAPTER    XII. 

VITAL    STATISTICS. 

SCIENCE  is  classified  knowledge.  By  arranging  known 
facts  and  units  into  groups,  and  considering  them  from 
different  points  of  view,  we  discover  the  scope  of  a  partic- 
ular science,  and  are  also  led  to  the  discovery  of  new  facts. 

In  hygiene  it  is  necessary  to  have  this  classification  of 
facts  to  know  what  progress  we  are  making,  for  the  true 
test  of  any  sanitary  procedure  is  its  efficacy  in  preserving 
health  and  preventing  disease,  and  we  cannot  know 
whether  it  is  efficient  or  not  unless  we  tabulate  and  study 
the  results  and  at  the  same  time  eliminate  disturbing  fac- 
tors. In  this  connection  it  is  to  be  noted  that  our  facts 
must  be  accurate  and  derived  from  sufficient  experience, 
and  that  the  disturbing  factors  are  especially  liable  to  be 
numerous. 

It  is  evident  that  we  may  study  disease  by  direct  obser- 
vation at  the  bedside  and  at  the  post-mortem  table,  or  by 
experiment;  and  while  our  knowledge  in  the  past  has  been 
gained  principally  by  the  former  method,  we  now,  since 
the  advent  of  modern  bacteriology,  may  further  investi- 
gate many  diseases  by  reproducing  them  in  susceptible 
animals.  In  this  way  we  soon  learn  that  some  diseases 
are  much  more  preventable  than  others,  and  we  endeavor 
to  discover  the  respective  causes  and  predisposing  condi- 
tions of  each  that  we  may  the  more  readily  estimate  their 
effects  and  take  measures  to  restrict  and  prevent  their 
action . 

Our  observations  may  be  of  two  kinds  :    1.  By  noting 


328    ^  MANUAL  OF  HYGIENE  AND  SANITATION. 

and  comparing  individual  cases,  or  by  following  the  track 
of  a  particular  outbreak  or  epidemic.  2.  By  observing 
large  classes  and  groups  of  men,  which  necessitates  a  record 
of  births,  marriages,  diseases,  and  deaths.  The  considera- 
tion of  such  records  constitutes  the  study  of  vital  statistics, 
the  most  important  object  of  which  is,  as  Dr.  Billings  says, 
"  to  give  warning  of  the  undue  increase  of  disease  or  death 
presumed  to  be  due  to  preventable  cause,  and  also  to  indi- 
cate the  localities  in  which  sanitary  effort  is  most  desirable 
and  most  likely  to  be  of  use."  The  reader  will  also  notice 
how  the  study  of  vital  statistics  broadens  out  into  the 
science  of  demography — the  study  of  the  life  of  people 
and  communities. 

At  this  point  it  will  be  well  to  note  certain  elementary 
principles  which  must  be  observed  in  any  statistical  in- 
quiry, in  order  that  the  results  of  that  inquiry  may  have 
any  value  whatever.  These  are: 

1.  Our  facts,  or  numerical  units ,  must  have  precise,  defi- 
nite, and  constant  characteristics.     For  example,  in  tabu- 
lating the  death-  or  sick-rate  from  typhoid  fever,  every  case 
used   in   the   calculation    must   be   accurately  diagnosed 
and  must  be  undoubtedly  one  of  that  disease.     If  there 
is  any  doubt  as  to  preciseness,  it  is  better  to  omit  that  unit. 

2.  The  units  are  to  be  arranged  into  groups.     These 
groups  must  have  dividing  characteristics  so  definite  that 
there  can  be  no  doubt  into  which  group  each  unit  will 
come.     No  unit  must  be  in  more  than  one  group  at  one 
time.     It  is  difficult  to  group  complex  facts  so  as  to  prop- 
erly analyze  them  and  to  discover  all  possible  phases. 

3.  Having  decided  and  arranged  the  groups,  we  must 
have  a  constant  numerical  standard  by  which  the  relation 
of  the  various  groups  to  the  total  units  may  be  expressed. 
It  is  generally  100  or  some  multiple  of  100. 


VITAL  STATISTICS.  329 

4.  We  must  determine  the  variation  in  the  proportion 
or  relation  of  the  component  groups  to  the  whole  in  similar 
series  of  cases.  While  only  an  approximation  to  an  inva- 
riable proportion  may  be  had  in  any  one  series,  it  may  be 
shown  mathematically  that  as  the  number  of  units  in  the 
series  increase  there  is  a  greater  probability  that  the  pro- 
portions will  remain  the  same,  and  that  we  may  calculate 
the  limits  of  variation  by  Poisson's  formula,  as  follows: 
If,  in  the  formula  m  -f-  n  =•  q,  m  be  the  number  of  units 
in  one  group  and  n  the  number  in  the  other,  the  propor- 

tion of  m  to  q  will  be  —  ,  and  of  n  to  q,  U  ,  and  these  propor- 
tions will  vary  in  succeeding  series  within  the  limits  indi- 
cated by  2  +  1  -  —1  Consequently,  the  greater  the  value 


__ 
of  <?,  the  less  will  be  that  of  2  -y  —    —  ,  or  the  limit  of  varia- 

#3 

-         m       i     n 

tion  from       and    _. 

q  q 

Example  :  Suppose  that  in  a  series  of  1000  cases  of 
typhoid  fever  700  recover;  then,  according  to  the  above 
formula,  the  limit  of  variation  in  the  next  series  of  1000 
similar  cases  would  be  40,  and  the  recoveries  would  be 
between  660  and  740. 

The  arithmetical  mean  is  usually  employed  in  medical 
inquiries,  though  the  increase  in  population  is  estimated 
by  geometrical  progression.  The  probable  error  or  vari- 
ation from  the  arithmetical  mean  is  about  two-thirds 
(0.6745)  of  the  mean  error,  which  latter  is  the  mean  of  the 
mean  error  in  excess  and  the  mean  error  in  deficiency.  The 
mean  error  in  excess  is  the  difference  between  the  mean  of 
the  series  and  the  mean  of  all  the  units  of  the  series  above 
the  mean.  The  mean  error  in  deficiency  is  the  difference 


330 


MANUAL  OF  HYGIENE  AND  SANITATION. 


between  the  mean  of  the  series  and  the  mean  of  the  units 
below  the  mean. 

The  relative  value  of  two  series  is  as  the  reciprocals  of 
the  squares  of  their  probable  errors.  Thus  if  the  probable 
error  of  series  A  is  10  per  cent,  and  that  of  B  is  2  per 
cent.,  the  value  of  A  to  B  will  be  as  y^  to  ^,  or  B  will 
be  twenty-five  times  as  valuable  as  A. 

FIG.  61. 


Graphic  chart,  showing  percentages  of  typhoid-fever  deaths  in  total  mortality 
in  four  cities.  Unbroken  line,  Chicago ;  lower  line,  New  York ;  short  dashes, 
Philadelphia ;  long  dashes,  Boston. 

The  relative  value  of  two  or  more  series  is  also  as  the 
square  roots  of  the  numbers  of  units  in  the  respective 
series.  From  the  above  it  is  evident  that  the  results  from 
an  average  cannot  be  absolutely  applied  to  any  particular 
case,  for  there  is  always  the  chance  of  such  variation  as 
may  be  determined  by  Poisson's  formula  or  by  the  estima- 
tion of  the  probable  error.  We  apply  averages  to  the 
aggregates  of  facts,  and  they  will  approach  exactitude  if 


VITAL  STATISTICS.  331 

they  are  founded  on  a  sufficient  number  of  facts.  We 
must  be  careful  in  estimating  the  value  of  means  and  aver- 
ages and  in  giving  credit  or  blame  accordingly.  Dr.  Guy 
says  :  " Averages  are  numerical  expressions  of  probabili- 
ties; extreme  values  are  expressions  of  possibilities.7' 

Statistical  results  are  frequently  expressed  by  graphic 
representations  (see  Fig.  61),  and  these  are  very  valuable, 
especially  for  class  or  similar  demonstration. 

The  numerical  units  employed  in  the  study  and  the  cal- 
culations of  vital  statistics  are  persons  living  and  persons 
dead,  and  the  groups  into  which  these  units  are  classified 
are  characterized  by  such  distinctions  as  age,  sex,  occupa- 
tion, locality,  etc.  The  sources  from  which  we  derive  our 
information  regarding  these  units  are  two,  viz.,  the  census 
or  count,  which  every  civilized  country  makes  period- 
ically, and  the  returns  of  births,  marriages,  deaths,  and 
cases  of  contagious  disease  made  to  local  governing  sani- 
tary bodies,  such  as  boards  of  health,  etc.  These  latter 
returns  localize  the  units  and  help  especially  in  the  classi- 
fication, in  which  locality  is  a  factor. 

The  census  returns  give  not  only  the  population,  but 
particulars  as  to  sex,  age,  race,  occupation,  etc.  Of  these 
the  age-record  is  most  important,  as  the  death-rate  varies 
most  according  to  age. 

The  natural  increment  of  a  population  is  the  excess  of 
births  over  deaths,  but  the  actual  increment  differs  from 
this,  however,  according  to  the  difference  between  emigra- 
tion and  immigration.  And  as  the  rate  of  increase  does 
not  always  remain  the  same,  estimates  of  population  at 
times  other  than  of  the  census  cannot  be  exactly  accurate. 
Thus,  we  may  have  a  lowered  death-rate  and  yet  a  decrease 
in  both  the  natural  and  actual  increment,  owing  to  a  greatly 
lowered  birth-rate  and  to  increased  emigration,  both  of 


332    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

which  may  be  primarily  due  to  a  long  period  of  oppression 
or  financial  distress.  However,  to  estimate  the  population 
for  times  other  than  the  census  year,  we  assume  that  the 
rate  of  increase,  whether  positive  or  negative,  that  pre- 
vailed between  the  last  two  census  enumerations,  will  con- 
tinue until  the  next  is  taken. 

Now,  as  populations  increase  in  regular  geometrical 
progression  when  the  rate  of  increase  is  constant,  which 

we  assume,  it  can  readily  be  shown  that  log.  R  =  —   (log. 

P'  —  log.  P),  where  R  is  the  annual  ratio  of  increase,  P  the 
population  of  the  census  before  the  last,  and  P'  the  popu- 
lation of  the  last  census.  If  we  now  multiply  the  log.  of 
R,  the  annual  ratio  of  increase,  by  the  number  of  years 
since  the  last  census,  and  add  to  it  the  log.  of  the  last 
census  (log.  P'),  we  will  have  the  log.  of  the  population 
at  the  middle  of  the  present  year — e.  g. , 

8  (log.  of  the  pop.  1890  —  log.  pop.  1880) 

~IO~ 

+  log.  pop.  1890  =  log.  of  the  population  on  June  30, 
1898. 

For  the  reasons  already  given,  such  an  estimate  will 
not  be  absolutely  accurate,  and  it  would,  consequently,  be 
well  to  have  a  census  taken  every  five  years  for  certain 
data.  The  more  accurate  the  estimate  for  any  year  hap- 
pens to  be,  the  more  reliable  will  be  the  statistical  results. 
It  is  also  to  be  noted  that  in  this  country  the  census  is 
taken  at  the  middle  of  the  year,  and  that  death-rates,  etc., 
are  based  on  the  population  estimated,  as  above,  for  the 
middle  of  the  given  year. 

We  may  also  estimate  the  population  from  the  number 
of  houses  and  use  this  as  a  check  on  the  above  estimate. 
The  number  of  persons  living  in  each  house  averages  about 


VITAL  STATISTICS.  333 

the  same  for  each  city,  but  differs  for  different  cities. 
Local  authorities  always  tend  to  overestimate  the  popula- 
tion, and  a  police  census  is  invariably  too  high.  Another 
method  of  approximately  estimating  the  population  in 
small  and  slowly  increasing  districts  is  to  add  to  the  pop- 
ulation of  the  last  census  one-tenth  of  the  difference 
between  it  and  the  population  of  the  preceding  census  for 
every  year  since  the  last  census. 

As  has  been  stated,  we  get  the  number  of  births,  mar- 
riages, deaths,  etc.,  from  the  registration  records,  the 
proper  data  being  furnished  to  the  registration  bureau  by 
duly  authorized  persons.  For  instance,  the  law  should 
require  a  burial  permit  for  each  death  in  order  to  identify 
the  person  and  to  guard  against  criminal  acts  or  neglect, 
and  the  death  certificate  on  which  the  burial  permit  is 
issued  should  give  the  name,  sex,  color,  age,  occupation, 
and  especially  the  cause  of  death  of  the  deceased.  The 
diagnosis  concerning  this  last  item  should  be  as  correct  as 
possible,  and  the  primary  as  well  as  the  secondary  cause 
of  death  should  be  given.  And  while  it  is  difficult  to 
determine  the  actual  cause  of  death  in  many  cases  without 
a  post-mortem  examination,  there  is,  fortunately,  not  much 
uncertainty  usually  in  diagnosing  the  diseases  of  which 
we  most  want  statistical  information,  especially  the  so- 
called  preventable  or  infectious  diseases. 

As  a  consequence  of  the  above,  the  certificate  as  to  the 
cause  of  death  will  need  to  be  signed  by  some  one  com- 
petent to  determine  that  cause,  viz.,  by  an  educated  physi- 
cian; and  it  is,  therefore,  necessary  that  the  State  should 
define  who  is  and  who  is  not  an  "  educated  physician. " 
And  as  this  information  and  the  other  required  returns 
which  the  physician  makes,  as  well  as  his  professional 
services  in  general,  are  for  the  sake  and  benefit  of  the 


334    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

citizens  of  the  State,  it  is  evidently  to  the  State's  interest 
that  it  be  very  careful  and  explicit  as  to  the  qualifications 
of  the  physicians  whom  it  allows  to  practise  within  its 
borders. 

Another  reason  for  the  enforced  return  of  a  certificate 
and  the  issuance  of  a  burial  permit  for  every  death  is, 
that  that  is  about  the  only  way  in  which  it  is  possible  to 
secure  a  record  of  all  the  deaths.  Any  system  for  col- 
lecting the  list  of  deaths  only  at  the  end  of  the  year  will 
lose  from  25  to  40  per  cent,  of  the  number. 

The  gross  death-rate  varies  with  the  size  of  the  com- 
munity. Newly  settled  communities  have  a  lower  death- 
rate  than  older  ones,  because  the  proportion  of  adults  is 
larger  and  of  children  smaller  in  the  former.  With 
large  communities  and  short  periods  the  probabilities  of 
error  are  very  great,  and  the  longer  the  period  the  less 
likelihood  of  error.  Birth-,  marriage-,  and  death-rates 
are  usually  calculated  as  rates  per  thousand  of  the  popula- 
tion living  at  tha  middle  of  the  given  year,  and  are  deter- 
mined by  multiplying  the  number  of  births,  marriages,  or 
deaths  by  1000,  and  dividing  the  product  by  the  population. 

Fair  death-rates  are  9  to  16  per  1000  in  rural  districts 
and  small  villages;  14  to  18  per  1000  in  towns  of  5000 
to  20,000;  17  to  20  in  cities  of  25,000  to  100,000,  and 
18  to  21  in  cities  over  100,000.  If  the  death-rates  are 
much  lower  than  this,  the  chances  are  that  the  population 
has  been  overestimated  or  that  all  deaths  have  not  been 
recorded.  If  more  than  this,  there  is  probably  some 
special  cause  for  the  high  mortality. 

In  statistical  computations  we  must  exclude  the  popula- 
tions and  deaths  in  hospitals,  prisons,  etc. ,  except  for  such 
of  the  inmates  as  belong  to  the  district  in  which  such 
institution  is  located. 


VITAL  STATISTICS.  335 

To  find  the  weekly  or  daily  death-rate,  the  number  of 
deaths  for  the  week  or  day  must  be  divided  by  the  so- 
called  weekly  or  daily  population  :  the  weekly  population  = 


The  monthly  population  equals  the  daily  population  mul- 
tiplied by  the  number  of  days  in  the  month. 

The  zymotic  death-rate  is  the  rate  from  the  seven  princi- 
pal zymotic  or  infectious  diseases,  viz.,  smallpox,  measles, 
scarlatina,  diphtheria,  whooping-cough,  fever  (typhoid, 
typhus,  or  other  continued  fever),  and  diarrhoea.1  It  is 
given  per  1000  of  population,  and  in  the  same  way  we  can 
give  the  special  rate  for  any  particular  disease.  For  ex- 
ample, the  zymotic  death-rate  for  England  and  Wales 
from  1861  till  1870  was  4.11,  for  1871-80  it  was  3.36,  and 
for  1881-90,  2.30;  a  striking  proof  of  the  decided  benefits 
following  proper  attention  to  hygiene  and  sanitation. 

The  mortality  from  certain  diseases  is  affected  by  age, 
sex,  race,  occupation,  density  of  population,  seasons, 
cyclical  changes,  etc. 

Contrary  to  the  general  rule,  the  rate  of  infant  mortality 
is  not  expressed  per  thousand  of  population,  but  measured 
by  the  proportion  of  deaths  of  infants  under  one  year  to 
the  births  registered  in  that  year,  and  is  determined  by 
multiplying  the  number  of  deaths  by  1000  and  dividing 
the  product  by  the  number  of  births. 

The  infant  mortality-rate  is  always  high,  owing  to  vari- 
ous causes;  viz.,  early  marriages  and  weakly  parents, 
hereditary  tendencies  or  diatheses,  insanitary  surround- 
ings and  unfavorable  social  conditions,  improper  feeding, 
insufficient  clothing,  infant  life  insurance,  etc. 

1  Wilson  :  Hahd-Book  of  Hygiene,  p.  566. 


336    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

Death-rates  vary  greatly  for  the  different  ages,  being 
much  higher  for  the  first  five  years  of  life.  For  this 
reason,  it  is  well  to  express  the  death-rate  of  children 
tinder  five  as  the  rate  per  thousand  of  the  children  under 
that  age,  rather  than  as  a  percentage  of  the  total  number 
of  deaths.  Otherwise,  a  town  with  a  large  number  of 
children  might  apparently  have  an  abnormally  high  death- 
rate.  There  might  also  be  a  difference  in  the  death-rates 
of  two  localities  due  to  sex-distribution,  for  the  sexes  differ 
in  their  susceptibility  and  resistance  to  the  various  dis- 
eases. More  boys  are  born  everywhere  than  girls,  but 
more  males  die  than  females,  so  that  the  tendency  is  to  a 
preponderance  of  the  latter,  except  in  newly  settled  coun- 
tries or  localities.  Age-  and  sex-distribution  favor  a  low 
mortality  in  rapidly  increasing  towns,  new  localities,  and 
manufacturing  districts;  in  rural  districts  they  tend  to 
increase  the  death-rate. 

Consequently,  when  the  death-rates  of  two  or  more 
towns  or  localities  are  to  be  compared,  there  must  be  cor- 
rections for  age-  and  sex-distribution.  The  mean  annual 
death-rate  of  the  country  for  the  decade  preceding  the  last 
census  for  each  age  and  sex  is  applied  to  the  town  or  dis- 
trict, with  age-  and  sex-distribution  according  to  the  last 
census.  The  total  number  of  deaths  thus  calculated,  mul- 
tiplied by  1000,  and  divided  by  the  population  of  the  last 
census,  gives  the  standard  death-rate  of  that  town.  The 
mean  annual  death-rate  of  the  country  divided  by  the 
standard  death-rate  gives  the  factor  for  correction,  which 
being  multiplied  by  the  recorded  death-rate  of  any  year 
gives  the  corrected  death-rate.  The  comparative  mortality 
figure  is  determined  by  multiplying  the  corrected  local 
death-rate  by  1000  and  dividing  by  the  death-rate  for  the 
whole  country,  and  only  indicates  that  the  same  popula- 


VITAL  STATISTICS.  337 

tion  which  gave  1000  deaths  in  the  whole  country  gave  or 
would  have  given  so  many  deaths  in  the  town  or  district 
in  question. 

The  morbidity-  or  sick-rate  of  a  community  is  difficult 
to  estimate,  since  there  is  usually  no  complete  record  and 
registration  of  cases  of  disease.  Where  returns  are  re- 
quired to  be  made  of  the  infectious  diseases,  the  morbidity 
due  to  them  may  be  determined  in  the  same  way  as  the 
mortality  for  the  locality.  It  is  estimated  that  there  is  a 
total  of  about  two  years'  sickness  in  a  community  for 
every  death,  and  members  of  beneficial  societies  are  said 
to  average  about  one  and  one-half  weeks7  sickness  annu- 
ally. In  this  connection,  the  following  definitions  are 
given  of  terms  that  are  employed  in  discussions  of  vital 
statics,  especially  in  relation  to  longevity: 

The  mean  age  at  death  of  a  population  is  the  average 
age  at  which  death  occurs  in  that  population,  and  is  indi- 
cated by  the  total  of  the  ages  at  death  divided  by  the 
number  of  deaths.  Inasmuch  as  it  depends  largely  on 
the  age-distribution  of  the  population,  it  is  neither  a  good 
test  of  longevity  nor  of  sanitary  conditions,  except  when 
it  is  calculated  or  taken  from  life-tables  for  an  entire 
generation. 

The  probable  duration  of  life  is  the  age  at  which  any 
number  of  children  born  will  be  reduced  one-half,  the 
chances  thus  being  even  that  each  will  survive  to  that  age. 

For  a  million  children  the  probable  duration  of  life  is 
for  males  less  than  forty-five  years;  for  females,  forty- 
seven  years. 

The  mean  duration  of  life  is  the  same  as  the  mean  age 
at  death  when  the  population  is  stationary  as  to  age-  and 
sex-distribution.  Otherwise,  it  is  indicated  by  the  mean 
after-lifetime. 


338    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

The  expectation  of  life  is  the  mean  after-lifetime  of  a 
person  at  any  age,  as  indicated  by  a  life-table,  or,  in  other 
words,  it  is  the  average  number  of  years  which  persons  of 
that  age  continue  to  live.  At  birth  it  is  identical  with 
the  mean  duration  of  life,  and  "  as  applied  to  communi- 
ties, it  is  the  mean  lifetime  of  a  generation  of  persons 
traced  by  the  life-table  method  from  birth  to  death,  and  is 
the  only  true  test  of  the  health  of  populations."  Accord- 
ing to  Dr.  Farr,  "  a  life-table  is  a  barometer  which  indi- 
cates the  exact  measure  of  the  duration  of  life  under  given 
Circumstances,  and  is  indispensable  in  gauging  the  influ- 
ence of  sanitary  or  insanitary  conditions." 

The  essential  factors  of  a  life-table  are  the  number  and 
ages  of  the  living  and  the  number  and  ages  of  those  that 
die,  and  these  factors  are  obtained  from  the  mean  popula- 
tion for  each  age  and  sex  and  from  the  total  death  returns 
between  two  censuses. 


CHAPTER    XIII. 

THE    EXAMINATION   OF   AIR,  WATER,   AND   FOOD. 

IN  this  final  chapter  the  author  has  endeavored  to 
arrange  a  series  of  methods  for  the  examination  or  analy- 
sis of  the  subjects  respectively  considered,  in  such  a  manner 
that  any  one  who  has  had  a  little  laboratory  experience  may 
be  enabled  to  determine  their  hygienic  condition,  sanitary 
influence  or  degree  of  purity,  and  this  at  the  cost  of  a 
minimum  of  time  and  expense. 

The  methods  outlined  have  been  selected  from  a  variety 
of  sources,  and  some  have  been  specially  modified  for  the 
purpose;  so  that  while  it  is  not  claimed  that  they  will  give 
the  absolutely  accurate  results  desired  by  the  professional 
bacteriologist  or  chemist,  it  is  believed  that,  if  carefully 
carried  out,  they  will  not  fail  to  yield  the  information 
sought  for,  viz.,  whether  the  sample  of  air,  water,  or  food 
examined  is  sanitarily  pure  or  safe  for  use  within  the 
accepted  limits. 

Only  such  apparatus  is  to  be  used  as  can  be  readily 
obtained  or  improvised  without  much  expense,  and  every 
effort  has  been  made  to  render  everything  clear  to  the 
student  and  reader,  so  that  he  may  not  hesitate  to  under- 
take the  necessary  investigation  whenever  occasion  requires 
or  an  opportunity  offers. 

For  further  details  regarding  any  of  the  methods,  should 
these  be  found  necessary,  reference  may  be  made  to  the 
text-books  indicated,  as  they  will  render  clear  any  points 
that  may  here  seem  uncertain  or  abstruse. 


340    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

Air. 

The  solid  impurities  in  the  atmosphere  may  be  collected 
for  microscopical  examination  as  follows:  Tightly  cork  a 
large  glass  funnel  and  fill  it  with  cracked  ice.  As  the  aque- 
ous vapor  of  the  air  condenses  on  the  exterior,  the  dust  par- 
ticles adhere  to  the  moistened  glass,  and  are  carried  down 
by  the  condensed  water  into  a  vessel  placed  below,  in 
which  they  are  allowed  to  settle.  From  this  they  are 
transferred  by  means  of  a  pipette  to  clean  slides  and 
examined  under  the  microscope.  Dr.  Dixon's  apparatus 
may  often  be  used  advantageously,  especially  where  it  is 
desired  to  examine  the  dust  in  the  air  of  a  number  of 
localities  within  a  short  time. 

To  make  a  qualitative  bacteriological  examination  the 
air  may  be  drawn  through  sterilized  glass  tubes  coated 
interiorly  with  gelatin.  Bacteria  and  their  spores,  moulds, 
etc.,  adhere  to  this  coating,  and  from  each  individual  or 
group  of  individuals  colonies  develop,  from  which  pure 
cultures  and  subsequent  bacteriological  experiments  may 
be  made;  or  the  sterilized  gelatine  may  be  exposed  in  flat 
(Petri)  dishes  to  the  air  for  a  short  time  to  allow  the  bac- 
teria, etc.,  to  fall  on  the  surface.  The  tubes  or  dishes  are 
then  covered  and  set  aside  to  allow  the  colonies  to  develop. 

To  make  a  quantitative  bacteriological  examination  a 
known  quantity  of  air  may  be  drawn  through  a  tube  filled 
with  sterilized  granulated  sugar.  The  sugar  is  then  trans- 
ferred to  tubes  or  flasks  of  melted  and  sterilized  gelatine, 
and  dissolves  and  leaves  the  bacteria,  etc.,  free  to  develop 
in  the  gelatine,  which  may  be  poured  out  before  cooling 
upon  sterilized  glass  plates  or  flat  Petri  dishes.  A  tem- 
perature just  sufficient  to  melt  the  gelatine  will  not  be  too 
high  to  harm  the  bacteria. 

The  number  of  colonies  that  develop  may  be  assumed 


EXAMINATION  OF  AIR,    WATER,  AND  FOOD.     341 

to  represent  the  number  of  living  micro-organisms  in  the 
volume  of  air  drawn  through  the  tube  or  that  fell  in  the 
dishes. 

Test  for  Carbonic-acid  Gas,  CO2.  Prof.  Boom's 
Modification  of  Wolpert's  Method.  Make  a  mark  on  any 
test-tube,  say  one  inch  from  the  bottom.  Fix  the  bulb  of 
an  atomizer  to  a  small  glass  capillary  tube,  sufficiently 
long  to  reach  to  the  bottom  of  the  test-tube,  and  in  such 
a  manner  that  a  definite  quantity  of  air  is  forced  from  the 
bulb  through  the  tube  at  each  compression.  To  use:  Fill 
the  test-tube  exactly  to  the  mark  with  a  saturated  solution 
of  lime-water,  take  the  apparatus  into  the  out-door  air  and 
find  put  how  many  compressions  of  the  bulb  are  needed, 
driving  the  air  slowly  through  the  lime-water  each  time, 
to  make  the  lime-water  just  turbid  enough  to  obscure  a 
pencil-mark  on  white  paper  placed  beneath  the  test-tube 
and  viewed  from  above. 

Then  rinse  out  the  test-tube,  fill  exactly  to  the  mark 
again  with  lime-water,  and  repeat  the  process  in  the  room 
the  air  of  which  is  to  be  examined.  We  then  assume  that 
the  out-door  air  contains  the  normal  amount  of  CO2,  0.04 
per  cent,  (unless  we  happen  to  know  the  actual  amount  in 
the  atmosphere  at  the  time),  and  estimate  the  percentage 
of  CO2  in  the  air  of  the  room  by  the  following  proportion : 

The  number  of  compressions  of  the  bulb  required  in 
the  outer  air  :  the  number  of  compressions  required  in 
the  room  :  :  x  :  0.04;  x  =  the  percentage  of  CO2  in  the 
air  of  the  room.  If  the  actual  percentage  of  CO2  in  the 
outer  air  is  known,  substitute  this  for  the  0.04  per  cent, 
in  the  formula.  Care  must  be  taken  in  using  this  device 
not  to  draw  any  of  the  lime-water  up  into  the  bulb. 

A  Modification  of  Angus  Smith's  Method.  To  a  mode- 
rately large,  wide-mouth  bottle  (one  quart)  fit  a  perforated 


342    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

rubber  stopper,  the  perforation  being  just  large  enough 
to  admit  the  tip  of  a  1  c.c.  pipette,  fill  the  bottle  with 
the  air  of  the  room  by  filling  it  with  water  and  then 
emptying  it  in  the  room;  fit  in  the  stopper  and  introduce 
1  c.c.  at  a  time  of  a  standardized  alkaline  solution,  slightly 
colored  with  a  few  drops  of  a  neutral  alcoholic  solution  of 
phenol  phthaleine;  close  the  perforation  with  a  piece  of  glass 
rod  and  shake  the  bottle  well  after  each  addition  of  the 
alkali,  noting  when  the  color  ceases  to  be  discharged  by  the 
CO2  of  the  contained  air.  Then,  since  the  quantity  used  of 
the  alkali  solution  indicates  a  certain  definite  amount  of  CO2: 

The  number  of  c.c.  used  multiplied  by  the  amount  of  C02 
each  c.c.  represents,  multiplied  by  100,  and  divided  by  the 
capacity  of  the  bottle  in  c.c.  less  the  number  of  c.c.  of  solution 
used  =  x  =  the  percentage  of  CO2  in  the  air  examined. 

A  suitable  alkaline  solution  may  be  prepared  as  fol- 
lows :  Dissolve  exactly  4.766  grammes  of  pure  sodium 
carbonate  (free  from  the  water  of  crystallization)  in  one 
litre  of  distilled  water.  Each  c.c.  of  this  solution  is 
equivalent  to  1  c.c.  CO2.  For  use  :  to  10  c.c.  of  this 
solution  add  a  few  drops  of  neutral  alcoholic  solution  of 
phenol  phthaleine  and  dilute  to  100  c.c.  Each-  c.c.  of 
this  dilute  solution  is  equivalent  then  to  0.1  c.c.  of  CO2, 
and  used  as  above  will  give  close  results.  The  phenol 
phthadeine  is  used  as  an  indicator,  as  it  loses  its  color  as 
soon  as  all  the  CO2  is  absorbed  and  the  alkalinity  of  the 
soda  solution  is  destroyed.  The  stock  solution  should  be 
kept  in  well-filled,  tightly  stoppered  bottles.  Example: 
If  9  c.c.  of  the  above  dilute  solution  be  used,  and  the 
capacity  of  the  bottle  is  1200  c.c.,  then 

9X0. 1X100  _     90    .         _  00755 

-1200=9-  -1T9T- 

the  percentage  of  CO2  in  the  air  of  the  room. 


EXAMINATION  OF  AIR,   WATER,  AND  FOOD.     343 

Pettenkofer's  Method.  Into  a  large,  clean  bottle  filled 
as  above  with  air  of  the  room,  50  c.c.  of  a  clear  saturated 
solution  of  lime-water  (or  barium  hydrate)  is  introduced, 
the  bottle  stoppered  and  then  well  shaken  so  that  the  air 
may  be  thoroughly  mixed  with  lime-water.  The  strength 
of  the  lime-water,  being  unknown,  is  determined  by  means 
of  a  solution  of  oxalic  acid  of  such  a  strength  that  1  c.c. 
corresponds  in  alkalinity  to  0.5  c.c.  of  CO2.  (Such  a 
solution  is  made  by  dissolving  exactly  2.84  grammes  of 
pure  crystallized  oxalic  acid  in  one  litre  of  distilled  water.) 

Into  25  c.c.  of  lime-water  in  a  beaker,  this  acid  solution 
is  run  from  a  graduated  burette  until  the  alkalinity  of  the 
lime-water  is  just  destroyed,  the  neutral  point  being  indi- 
cated either  by  means  of  a  few  drops  of  phenol  phthaleine 
solution  in  the  beaker,  or  by  turmeric  paper,  the  latter 
being  colored  brown,  and  the  phenol  phthaleine  retaining 
its  color  as  long  as  the  solution  is  alkaline.  When  the 
lime-water  is  exactly  neutralized  the  exact  amount  of  the 
acid  solution  used  is  noted.  Then,  after  the  time  necessary 
to  allow  the  complete  absorption  of  the  CO2  in  the  testing 
bottle  by  the  lime-water  therein,  viz.,  eight  to  ten  hours, 
25  c.c.  of  that  lime-water  is  measured  into  a  beaker  and 
the  alkalinity  determined  exactly  as  above  by  means  of 
the  oxalic-acid  solution. 

Now,  inasmuch  as  part  of  the  alkalinity  of  the  lime- 
water  in  the  bottle  has  already  been  neutralized  by  the 
carbonic  acid  in  the  air  of  the  bottle,  and  as  1  c.c.  of  the 
acid  solution  corresponds  to  0.5  c.c.  of  CO2,  it  will  re- 
quire less  of  the  acid  solution  to  neutralize  the  lime-water 
from  the  bottle  than  was  required  for  the  same  quantity 
of  stock  lime-water,  and  this  difference  expressed  in  c.c. 
will  express  the  number  of  c.c.  of  CO2  in  the  air  of  the 
bottle  or  of  the  room  from  which  it  was  taken. 


344    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

For,  though  each  c.c.  of  acid  solution  is  equivalent  to 
only  0.5  c.c.  of  CO2,  the  loss  of  alkalinity  of  only  one- 
half  the  lime-water  introduced  into  the  bottle  has  been 
determined  and  the  total  loss  of  alkalinity  would  have  to 
be  expressed  by  a  difference  of  twice  as  many  c.c.  of  acid 
solution  used  multiplied  by  0.5  c.c.  CO2.  The  quantity 
of  carbonic  acid  in  the  bottle  having  been  thus  deter- 
mined and  the  capacity  of  the  bottle  found  by  measuring 
the  quantity  of  water  it  will  hold,  the  percentage  of  car- 
bonic acid  in  the  air  is  readily  determined. 

Example  :  25  c.c.  of  stock  lime-water  requires  30  c.c. 
acid  solution;  25  c.c.  of  lime-water  from  bottle  requires 
27  c.c.  acid  solution. 

Therefore,  30  '  c.c.  —  27  c.c.  =  amount  of  carbonic 
acid  in  the  bottle,  which  contains  (for  example,  say) 
2550  c.c. 


Then  o=       =  °'12  per  cent  co°  in  the  air 

of  room  at  current  temperature  and  pressure. 

Water. 

To  test  for  color,  turbidity,  etc.,  compare  with  distilled 
water,  using  tall  glass  jars,  and  looking  down  through 
equal  depths  upon  a  white  surface.  The  smell  of  a  water 
may  be  detected  by  heating  it  to  about  140°  F.  for  a  few 
minutes  in  a  glass-stoppered  bottle.  This  test  may  or 
may  not  indicate  fecal  contamination.  Few  polluting 
impurities,  when  only  in  moderate  quantities,  give  any 
taste  to  water,  and  a  dangerously  polluted  water  may 
have  a  good  taste.  Iron  in  small  quantities,  one-fourth 
of  a  grain  to  a  gallon,  will  give  a  taste  to  the  water. 

Use  caution  in  tasting  suspicious  waters.     Aeration  is 


EXAMINATION  OF  AIR,   WATER,  AND  FOOD.     345 

indicated  by  the  lustre  of  the  water  and  by  the  presence 
of  air  bubbles  on  the  sides  and  bottom  of  the  vessel. 


FIG.  62. 


Bottle  for  collecting  water  at  different  levels. 

Test  for  Chlorine.  Solutions  required.  (I)  Standard 
nitrate  of  silver  solution :  to  1  litre  of  pure  distilled  water 
add  4.788  grammes  of  pure  silver  nitrate;  one  c.c.  of  this 
solution  is  equivalent  to  1  m.g.  of  chlorine.  (2)  Potas- 
sium chromate  solution — a  5  or  10  per  cent,  solution  of 


346    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

potassium  chroraate  made  up  in  distilled  water  free  from 
chlorine. 

Process.  To  100  c.c.  of  the  water  add  a  few  drops  of 
the  potassium  chromate  solution,  and  then  run  in  from  a 
burette  or  graduated  pipette  the  silver  solution,  adding  it 
drop  by  drop  and  stirring  the  water  with  a  glass  rod. 
Continue  until  a  faint  but  permanent  orange-red  tint  has 
been  produced,  showing  that  all  the  chlorine  has  combined 
with  the  silver,  the  persisting  reddish  color  being  due  to 
silver  chromate.  The  number  of  c.c.  of  silver  used  indi- 
cate the  number  of  m.g.  of  Cl  in  100  c.c.,  or  parts  per 
100,000;  this  multiplied  by  10  gives  the  number  of  m.g. 
of  Cl  in  one  litre,  or  parts  per  million.  If  the  water 
contained  but  little  chlorine,  accuracy  will  be  furthered 
by  evaporating  250  of  the  water  to  50  c.c.  over  a  water- 
bath,  and  proceeding  as  above;  the  result  multiplied  by  4 
will  give  the  amount  of  chlorine  in  one  litre. 

Test  for  Nitrates.  Solutions  required.  1.  Phenol- 
sulphonic  acid:  6  grammes  of  pure  carbolic  acid;  37  c.c. 
strong  sulphuric  acid,  and  3  c.c.  distilled  water.  2. 
Standard  potassium  nitrate  solution:  Add  0. 722  grammes 
of  fused  potassium  nitrate  to  one  litre  of  distilled  water. 
Each  c.c.  of  this  solution  contains  0.1  m.g.  of  nitrogen 
as  nitrates.  The  water  used  in  making  the  solution  must 
be  free  from  nitrates. 

Process.  Evaporate  10  c.c.  of  the  water  to  be  exam- 
ined (or  25  c.c.  if  it  is  presumably  low  in  nitrates)  just  to 
dryness,  add  1  c.c.  of  phenol-sulphonic  acid,  stir  with  a 
glass  rod,  and  add  1  c.c.  of  distilled  water  and  three  drops 
of  H2SO4,  warm,  and  add  25  c.c.  distilled  water  and 
NH4HO  to  excess  and  dilute  with  water  to  50  c.c. 

Treat  1  c.c.  of  the  standard  solution  in  an  exactly  sim- 
ilar manner  and  compare  the  tints  produced,  diluting  the 


EXAMINATION  OF  AIR,   WATER,  AND  FOOD.    347 

darker  until  the  tints  match  exactly,  and  calculating  the 
amount  of  nitrogen  present  by  the  amount  of  dilution 
necessary — e.  g.,  the  tint  from  1  c.c.  of  standard  potassium 
nitrate  solution  is  darker  and  needs  the  addition  of  50  c.c. 
more  water — i.  e.,  up  to  100  c.c.  Therefore,  100  c.c.  :  50 
c.c.  :  :  0.1  m.g.  N  :  x  =  0.05  m.g.  nitrogen  as  nitrates  in 
the  10  c.c.  of  water  examined.  The  test  depends  on  the 
fact  that  the  phenol-sulphonic  acid  is  converted  by  the 
nitrates  into  picric  acid,  which  goes  to  form  ammonium 
picrate  upon  the  addition  of  ammonia  giving  a  yellow 
tint  to  the  water.  The  amount  of  picric  acid  and  picrate 
formed  depends  on  the  amount  of  nitrates  present. 

Test  for  Nitrites.  Solutions  required.  1.  Sulphanilic 
acid:  dissolve  0.5  gramme  of  sulphanilic  acid  in  150  c.c. 
of  dilute  acetic  acid,  sp.  gr.  104.  2.  Naphthylamine 
acetate:  boil  0.1  gramme  of  solid  naphthylamine  in  20 
c.c.  of  distilled  water,  filter  through  a  plug  of  washed 
absorbent  cotton,  and  mix  the  filtrate  with  180  c.c.  of 
dilute  acetic  acid.  3.  Standard  sodium  nitrite  solution: 
dissolve  0.275  gramme  of  pure  silver  nitrite  in  pure 
water  and  add  a  dilute  solution  of  pure  sodium  chloride 
until  a  precipitate  ceases  to  form,  and  dilute  to  250  c.c. 
with  pure  water.  For  use,  dilute  10  c.c.  of  this  solution 
to  100  c.c.  Each  c.c.  of  the  dilute  solution  contains  0.01 
m.g.  nitrogen  as  nitrites.  Keep  the  solution  in  the  dark 
when  not  in  use.  All  water  in  these  solutions  must  be 
free  from  nitrites;  likewise  all  water  used  in  tests,  except 
the  sample  under  examination. 

Process.  To  25  c.c.  of  water  to  be  examined,  placed 
in  a  cylindrical  vessel,  add  2  c.c.  each  of  sulphanilic  acid 
and  naphthylamine  acetate  solution,  using  a  separate 
pipette  for  each;  in  a  similar  cylindrical  vessel  dilute  1 
c.c.  of  the  standard  sodium  nitrite  solution  to  25  c.c.  with 


348    ^  MAX  UAL  OF  HYGIENE  AND  SANITATION. 

nitrogen-free  distilled  water,  and  add  the  same  quantity  of 
the  above  reagents  to  it;  compare  the  colors  at  the  end  of 
five  minutes  and  estimate  the  amount  of  nitrites  by  diluting 
the  darker  tint  until  it  matches  the  lighter;  the  result  will 
give  the  quantity  of  nitrogen  as  nitrites  in  the  water,  and 
should  not  be  over  a  trace.  The  above  test  is  a  very 
delicate  one. 

Test  for  Hardness.  Solutions  required.  1.  Soap  solu- 
tion: dissolve  10  grammes  of  castile  soap  in  one  litre  of 
weak  (35  per  cent.)  alcohol.  2.  Standard  lime  solution: 
dissolve  1.11  grammes  of  calcium  chloride  in  1  litre  of 
distilled  water;  1  c.c.  of  this  solution  is  equivalent  to  1 
m.g.  of  calcium  carbonate. 

Process.  Find  out  how  much  soap  solution  is  needed 
to  make  a  lather  with  100  c.c.  of  distilled  water,  as  fol- 
lows:  Place  the  water  in  a  flask  holding  about  250  c.c., 
and  run  in  the  soap  solution  from  a  burette,  a  few  drops  at 
a  time,  corking  and  shaking  the  flask  well  after  each  addi- 
tion ;  the  lather  should  have  a  depth  of  at  least  one-fourth 
of  an  inch  and  be  permanent  for  five  minutes.  Then 
standardize  the  soap  solution  by  diluting  5  c.c.  of  the  stand- 
ard lime  solution  to  100  c.c.  with  distilled  water,  and  find 
out  how  many  c.c.  of  the  soap  solution  are  necessary  to 
make  a  permanent  lather  as  above  with  it;  this  quantity, 
less  the  number  of  c.c.  needed  to  make  a  lather  with  100 
c.c.  of  distilled  water,  represents  the  amount  of  soap  solu- 
tion that  will  neutralize  5  m.g.  CaCO3  or  its  equivalent; 
lastly,  determine  in  the  same  way  the  number  of  c.c.  of 
soap  solution  necessary  to  make  a  permanent  lather  with 
100  c.c.  of  the  water  to  be  examined;  subtract  the  quan- 
tity necessary  for  100  c.c.  distilled  water  and  estimate  the 
amount  of  CaCO3  or  its  equivalent  present,  as  follows — 
e.  g.,  it  takes  2  c.c.  of  soap  solution  to  make  a  lather  with 


EXAMINATION  OF  AIR,   WATER,  AND  FOOD.     349 

the  distilled  water,  and  12  c.c.  with  the  diluted  lime  solu- 
tion; then  12  c.c.  — 2  c.c.  =  10  c.c.  =  5  m.g.  CaCO3, 
and  each  c.c.  of  the  soap  solution  =  0.5  c.c.  of  the  stand- 
ard lime  solution,  or  0.5  m.g.  CaCO3;  consequently,  if 
100  c.c.  of  the  water  examined  require  17  c.c.  of  soap 
solution,  it  must  contain  (17 — 2)  X  0.5  =  7.5  m.g.,  and  1 
litre  of  water  contains  75  m.g.  of  calcium  carbonate  or  its 
equivalent. 

Tests  for  Lead,  Copper,  and  Iron.  To  50  or  100 
c.c.  of  water  in  a  white  porcelain  dish,  or  in  a  tall  glass  jar 
over  a  white  paper,  add  a  few  drops  of  ammonium  sul- 
phide; a  dark  coloration  or  precipitate  indicates  the  pres- 
ence of  either  lead,  copper,  or  iron,  due  to  the  formation  of 
their  respective  sulphides.  Then  add  a  few  drops  of  HC1 ;  if 
the  color  disappears  Fe  only  is  present;  if  it  persists  Pb  or 
Cu  is  present.  In  the  latter  case  add  a  few  drops  of  acetic 
acid  and  about  1  c.c.  of  a  strong  solution  of  potassium 
cyanide;  if  the  color  disappears  it  is  due  to  Cu;  if  it  per- 
sists it  is  due  to  Pb.  If  Pb  only  is  present  the  above  test 
will  detect  one-tenth  of  a  grain  per  gallon.  The  above 
tests  may  be  corroborated  as  follows :  Partly  fill  two  test- 
tubes  with  the  original  water;  to  one  add  a  little  potassium 
chromate  solution;  an  opacity  and  the  deepening  of  the 
color  to  canary  yellow  indicate  lead.  To  the  second  add 
a  drop  of  HC1  and  a  few  drops  of  potassium  ferrocyanide 
solution;  a  blue  color  indicates  iron,  either  ferrous  or  ferric; 
a  bronze  or  mahogany-red  color  indicates  copper. 

Quantitative  tests  for  the  above  metals  may  be  made 
by  making  standard  solutions  of  the  respective  elements, 
treating  a  measured  quantity  of  the  original  water  with 
the  proper  reagent  as  indicated  above,  and  comparing  the 
color  produced  with  that  given  by  a  definite  quantity  of 
the  respective  standard  solution. 


350    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

Test  for  Phosphates.  Solution  required.  Ammo- 
nium molybdate:  dissolve  10  grammes  of  molybdic  anhy- 
dride in  41.7  c.c.  of  NH4HO  (sp.  gr.  0.96)  and  pour 
slowly  into  125  c.c.  of  HNO3  (sp,  gr.  1.20);  allow  to 
stand  in  a  warm  place  for  several  days  until  clear. 

Process.  Slightly  acidulate  500  c.c.  of  water  with 
HNO3,  evaporate  to  50  c.c.,  and  add  a  few  drops  of  Fe2Cl6 
and  NH4HO  to  slight  excess;  filter,  dissolve  the  precipi- 
tate in  the  smallest  possible  quantity  of  HNO3  and  evapo- 
rate to  5  c.c. ;  heat  nearly  to  boiling,  add  20  c.c.  of 
ammonium  molybdate  solution;  keep  the  solution  warm 
for  one-half  hour.  If  there  is  an  appreciable  quantity  of 
precipitate,  collect  it  on  a  small  weighed  filter-paper,  wash 
with  distilled  water,  dry  at  100°  F.,  and  weigh.  The 
weight  of  the  precipitate  multiplied  by  0.05  gives  the 
amount  of  PO4  in  the  500  c.c.  of  water. 

Test  for  Free  and  Albuminoid  Ammonia.  Wank- 
lyn's  Method.  Solutions  required:  1.  Standard  ammo- 
nium chloride  solution:  dissolve  0.382  gramme  of  pure- 
dry  NaCl  in  100  c.c.  ammonia-free  water  ;  each  c.c.  of 
the  dilute  solution  contains  0.01  m.g.  of  nitrogen  as 
ammonia.  2.  Alkaline  potassium  permanganate  solution : 
dissolve  200  grammes  of  KHO  (in  sticks)  and  8  grammes 
of  potassium  permanganate  in  1  litre  of  distilled  water, 
evaporate  to  about  750  c.c.  to  drive  off  the  ammonia 
present  and  make  up  to  1  litre  again  with  ammonia-free 
water.  To  make  ammonia-free  water,  add  about  1 
grain  sodium  carbonate  to  the  litre  of  distilled  water  and 
boil  until  about  one-fourth  is  evaporated.  3.  Nessler's 
reagent:  dissolve  15  grammes  KI  in  100  c.c.  of  distilled 
water  and  17  grammes  HgCl2  in  300  c.c.  of  water;  add 
the  HgCl2  solution  to  the  KI  until  a  permanent  precipi- 
tate is  formed,  then  dilute  with  a  20  per  cent,  solution  of 


EXAMINATION  OF  AIR,   WATER,  AND  FOOD.     351 

NaHO  to  1000  c.c.,  add  HgCl2  solution  till  a  permanent 
precipitate  again  forms,  and  allow  to  stand  until  clear; 
this  reagent  gives  a  brown  or  yellowish-brown  coloration 
if  NH3  be  present  in  water,  and  improves  on  keeping. 

Process.  Place  500  c.c.  of  the  water  to  be  examined 
in  a  retort,  connect  with  a  condenser,  and  boil  gently  so 
that  the  water  may  distil  over  slowly.  The  retort,  and 
condenser  should  have  been  thoroughly  rinsed  with  am- 
monia-free water.  Collect  the  distillate,  50  c.c.  at  a  time, 
in  Nessler  tubes,  add  2  c.c.  of  Nessler's  reagent  to  each 
50  c.c.,  and  determine  the  amount  of  ammonia  or  nitrogen 
in  each  as  follows:  Place  in  another  Nessler  tube  50  c.c. 
ammonia-free  water  and  2  c.c.  Nessler's  reagent,  run  in 
from  a  burette  the  standard  ammonium  chloride  solution 
until  the  color  exactly  matches  that  of  the  first  50  c.c.  of 
the  distillate.  Repeat  the  process  with  each  50  c.c.  of 
distillate  until  the  test  shows  no  more  ammonia  is  coming 
over  from  the  retort.  The  total  amount  of  ammonium 
chloride  solution  used  indicates  the  total  amount  of  nitro- 
gen of  the  free  ammonia.  Usually  all  the  free  ammonia 
will  come  over  in  the  first  150  or  200  c.c.  of  distillate. 
Compare  the  colors  by  looking  down  through  the  tube  on 
a  white  surface.  If  the  first  50  c.c.  gives  a  precipitate 
with  the  Nessler  reagent  it  must  be  diluted  and  the 
amount  of  nitrogen  estimated  from  the  diluted  distillate. 
The  free  ammonia  being  determined,  allow  the  retort  to 
cool  and  add  to  the  water  remaining  in  it  50  c.c.  of  the 
alkaline  permanganate  solution.  This  converts  a  certain 
proportion  of  the  nitrogenous  organic  matter  into  ammo- 
nia; distil  as  before,  estimating  the  amount  of  nitrogen 
in  each  50  c.c.  of  the  distillate  until  no  more  ammonia 
comes  over.  The  amount  of  ammonium  chloride  solution 
thus  used  will  indicate  the  nitrogen  of  albuminoid  ammo- 


352    ^  MANUAL  OF  HYGIENE  AND  SANITATION. 

nia,  and  the  total  amount  of  ammonium  chloride  solution 
used  in  the  whole  process  gives  the  nitrogen  of  the  free 
and  albuminoid  ammonia  in  one  litre  of  water. 


Pood. 

Milk.  Good  Milk.  Characteristics :  Ivory  white, 
opaque,  neutral  or  slightly  alkaline  reaction,  no  sediment, 
no  unusual  or  offensive  taste  or  odor,  sp.  gr.  1029  or  above; 
cream,  10  to  40  per  cent,  by  volume;  fats  3  per  cent,  or 
more;  total  solids,  12.5  per  cent,  or  more. 

Water  is  indicated  by  low  specific  gravity  and  by  low 
percentage  of  cream. 

Skimming  is  indicated  by  a  slightly  raised  specific 
gravity  (2°),  by  a  low  percentage  of  cream,  and  by  a  poor 
color,  though  the  deterioration  in  color  may  be  disguised 
by  the  addition  of  annatto,  etc. 

Watering  and  skimming  are  indicated  by  lowered  specific 
gravity,  by  low  percentage  of  cream,  and  by  poor  color. 

The  specific  gravity  is  determined  by  the  lactometer,  in 
using  which  correction  must  be  made  for  temperature,  pro- 
vided the  latter  varies  much  from  60°  F.,  the  standard. 

The  percentage  of  cream  is  determined  by  the  cream 
gauge  or  creamometer;  the  milk  should  be  allowed  to 
stand  in  the  creamometer  for  at  least  eight  to  ten  hours, 
and  should  be  covered. 

A  very  high  percentage  of  cream  tends  to  lower  the 
specific  gravity  theoretically;  but  when  a  milk  is  rich  in 
fat  it  is  also  rich  in  solids  not  fat. 

An  acid  reaction,  unless  very  slight,  indicates  souring 
of  the  milk  or  the  addition  of  some  preserving  acid.  A 
strongly  alkaline  reaction  indicates  the  addition  of  some 
substance  like  chalk,  sodium  carbonate,  etc.,  to  increase 


EXAMINATION  OF  AIR,   WATER,  AND  FOOD.    353 

the  specific  gravity.  Such  addition  is  verified  by  an  excess 
of  total  solids,  and  by  the  effervescence  of  the  latter — after 
drying — upon  the  addition  of  a  drop  or  two  of  HC1. 

To  determine  the  percentage  of  total  solids:  Weigh  a 
small  evaporating  dish,  preferably  platinum,  add  5  or  10 
c.c.  of  milk,  and  weigh  dish  and  milk  to  get  weight  of 
milk;  evaporate  to  dryness  over  water-bath,  completing 
the  drying  in  a  water-oven  until  there  is  no  further  loss  of 
weight;  weigh  dish  and  contents  (total  solids);  subtract 
weight  of  dish,  multiply  by  100,  and  divide  by  weight 
of  milk.  Result :  the  percentage  of  total  solids. 

To  determine  the  percentage  of  ash:  Ignite  the  total 
solids  over  the  naked  flame  until  all  black  specks  have 
disappeared;  cool  and  weigh;  multiply  weight  of  ash  by  100, 
and  divide  by  weight  of  milk.  Result :  percentage  of  ash. 

To  determine  the  percentage  of  fats :  Proceed  as  above 
with  10  c.c.  of  milk,  and  evaporate  until  the  residue  is  a 
tenacious  pulp,  extinguish  the  flame,  fill  the  dish  half  full 
of  ether,  stir,  and  pound  the  residue  thoroughly  with  a 
glass  rod,  filter  through  a  small  filter-paper,  reserving  the 
filtrate;  add  more  ether  to  the  residue,  stir  as  before,  and 
filter,  repeating  the  process  three  times  or  till  the  residue 
is  perfectly  white;  wash  the  filter-paper  well  with  ether 
and  evaporate  all  the  ether  to  dryness;  weigh  the  residue 
— the  fat — multiply  by  100  and  divide  by  the  weight  of 
milk.  Result :  percentage  of  fat. 

Where  a  medical  centrifuge  is  available  for  use,  the 
following  method  for  the  fat-determination  will  be  found 
to  give  results  that  are  probably  accurate  to  within  one- 
fifth  of  1  per  cent,  of  fat : 

Two  solutions  are  necessary:  1.  Fusel  oil,  37  c.c.;  wood 
or  methyl  alcohol,  13  c.c.;  hydrochloric  acid,  50  c.c.  2. 
Sulphuric  acid,  sp.  gr.  1.83. 

23 


354 


MANUAL  OF  HYGIENE  AND  SANITATION. 


Into  the  milk  bottle,  which  is  made  to  fit  the  centrifuge 
and  which  has  a  long  graduated  neck,  5  c.c.  of  the  milk 
to  be  examined  is  introduced  by  means  of  a  pipette,  and 


FIG.  63. 


Bottle  lor  determining  percentage  of  fat  by  means  of  the  centrifuge. 

to  this  1  c.c.  of  the  alcohol  solution  (1)  is  added  and  the 
mixture  well  shaken  by  hand.  The  sulphuric  acid  is 
then  added,  little  by  little,  with  frequent  shaking,  until 


EXAMINATION  OF  AIR,    WATER,  AND  FOOD.     355 

the  bottle  is  filled  to  the  topmost  (zero)  graduation.  It 
is  then  rapidly  whirled  in  the  centrifuge  until  only  the  fat 
occupies  the  neck  as  a  clear  layer,  when  the  actual  per- 
centage can  be  read  from  the  graduations.  When  the  milk 
is  very  rich — i.  e.,  containing  more  than  5  per  cent,  of 
fat — it  will  be  necessary  to  dilute  the  milk  with  an  equal 
volume  of  water,  and  then  to  multiply  the  result  by  2. 
Likewise,  cream  should  be  diluted  with  four  parts  of 
water  and  the  result  multiplied  by  5.  The  same  principle 
is  employed  in  the  Babcock  and  other  cream  testers  now 
largely  used  by  dairymen,  etc. 

Test  for  annatto:  A  percentage  of  cream  considerably 
lower  than  the  color  of  the  milk  would  indicate  justifies 
the  suspicion  that  some  coloring  matter  has  been  used. 
This  is  frequently  annatto. 

Coagulate  one  ounce  of  milk  with  a  few  drops  of  acetic 
acid  and  heat,  strain,  and  press  out  excess  of  liquid  from 
curd;  triturate  the  curd  in  a  mortar  or  dish  with  ether,  de- 
cant ether  and  add  to  it  10  c.c.  of  a  1  per  cent,  solution  of 
caustic  soda;  shake,  and  allow  to  separate;  pour  off  the  upper 
layer  into  a  porcelain  dish,  put  in  two  small  disks  or  strips 
of  filter-paper;  evaporate  gently.  Annatto  will  dye  the 
disks  an  orange  or  buff  color.  Moisten  one  disk  with 
dilute  sodium  carbonate  to  fix  the  color;  touch  the  other 
disk  with  a  drop  of  stannous  chloride.  Annatto  will 
give  a  rich  pink  color.  This  test  is  sensitive  to  one  part 
of  annatto  in  1000  of  milk,  and  with  milk  in  any  condition. 

Test  for  boric  acid :  In  igniting  total  solids  boric  acid 
or  boron  gives  greenish  tinge  to  flame.  Place  in  a  porce- 
lain dish  5  c.c.  of  milk,  one  drop  of  strong  HC1  and  two 
of  a  saturated  tincture  of  turmeric.  Dry  on  a  water-bath, 
remove  as  soon  as  dry;  cool,  and  add  one  drop  of  ammonia 
on  a  glass  rod.  A  slaty-blue  color,  changing  to  green,  is 


356    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

given  if  borax  is  present.  This  test  will  show  one  one- 
thousandth  grain  of  borax.  Less  will  give  the  green 
color,  but  not  the  blue. 

Butter  and  Oleomargarine.  Good  butter  should  have 
good  taste,  odor,  and  color;  it  should  not  be  rancid,  and 
should  not  contain  too  much  water  nor  salt,  nor  should  it 
have  any  added  coloring  matter.  The  average  composition 
should  be  about  as  follows  :  Fat,  82  per  cent. ;  casein,  2 
per  cent,  (not  over  3  per  cent. ) ;  ash  or  salts,  2  per  cent. ; 
water  13  per  cent.  Butter  fat  is  a  compound  of  glycerin 
with  certain  fatty  acids,  some  of  them  volatile  and  soluble 
in  hot  water,  others  non-volatile  and  insoluble  in  hot  water. 

Oleomargarine  consists  of  ordinary  animal  or  vegeta- 
ble fats,  melted,  strained,  cooled  with  ice,  worked  up  with 
milk,  colored,  and  salted.  These  fats  are  usually  beef  or 
mutton  fat,  lard,  or  cotton-seed,  palm,  or  cocoanut  oil. 

If  care  and  cleanliness  are  observed  in  the  manufacture, 
oleomargarine  is  not  harmful  nor  innutritions,  but  it  should 
not  be  sold  as  butter. 

Fraud  is  to  be  detected  by  observing  the  difference  in 
composition  and  properties  of  the  fats.  For  instance  : 

BUTTER  FAT.  BEEP  FAT,  ETC. 

1.  The  specific  gravity  is  very  rarely  Beef  fat,  etc.,  is  never  above  904.5. 
below  910,  never  below  909.8. 

2.  The  soluble,  volatile  fatty  acids  Rarely  more  than  %  per  cent. ,  never 
average  between  6   and  7  per  cent.,  above  yi  per  cent. 

never  below  4.5  per  cent. 

3.  The    insoluble    fatty  acids  form          Generally  about  95  per  cent, 
about  88  per  cent,  of  the  total  weight 

of  butter  fat. 

4.  The  melting  point  of  the  fat  varies          Rarely,  if  ever,  above  82°  F. 
from  86°  to  94°  F. ;  is  usually  from  88° 

to  90°  F. 

5.  Is  readily  and  completely  soluble  Less  so  and  leaves  a  residue, 
in  ether. 

6.  Under  the  microscope  pure  butter  The  contours  of  the  small  oil  globules 
fat  consists  of  a  collection  of  small  oil  are  less  distinct,  and  the  larger  ones  are 
globules,  with  an  occasional  large  one.  more  numerous  and  irregular  in  size. 

No  crystals,  except  when  the  fat  has          Crystals  of  the  non- volatile  acids  are 
been  melted.  often  seen. 


EXAMINATION  OF  AIR,   WATER,  AND  FOOD.    357 

To  determine  the  specific  gravity :  Melt  a  quantity  of  the 
butter  in  a  beaker  in  a  water-bath  at  about  150°  F.  After 
a  time,  when  the  fat  is  perfectly  clear  and  transparent, 
carefully  decant  the  fat  from  the  lower  stratum  of  water, 
curd,  and  salt  into  a  fine  filter;  collect  the  filtrate  and  pour 
into  a  specific-gravity  bottle,  which  has  been  previously 
weighed,  both  when  empty  and  when  filled  with  distilled 
water  at  100°  F.  See  that  the  bottle  is  exactly  full  of  the 
fat,  wipe  clean,  and  weigh  when  the  temperature  is  as  near 
100°  F.  as  possible,  because  solidification  soon  begins 
below  this  temperature.  Subtract  the  weight  of  the 
bottle,  divide  by  the  weight  of  the  water  which  the  bottle 
contains,  and  multiply  by  1000;  the  result  is  the  specific 
gravity. 

To  find  the  melting  point :  Pour  a  little  melted  fat  into  a 
small  test-tube  (2"  x  J")  and  cool.  Partly  fill  two  beakers 
of  unequal  size  with  cold  water;  place  the  test-tube  in  the 
smaller  (taking  care  to  allow  no  water  to  mix  with  the 
fat),  and  the  smaller  in  the  larger,  and  gently  heat  the 
outer  beaker.  Suspend  a  thermometer  in  the  smaller,  near 
the  test-tube,  and  note  the  temperature  when  the  fat  begins 
to  melt;  this  is  the  melting  point. 

To  determine  the  percentage  of  insoluble  (non-volatile)  fatty 
acids:  To  6  grammes  of  butter  fat  add  50  c.c.  of  alcohol 
containing  2  grammes  of  caustic  potash  (KHO)  and  boil 
gently  for  fifteen  or  twenty  minutes  to  saponify  the  fat. 
Dissolve  the  soaps  thus  formed  in  150  to  200  c.c.  of  water, 
and  decompose  with  about  25  c.c.  of  dilute  hydrochloric 
acid.  The  separated  fatty  acids  are  poured  upon  a  weighed 
filter-paper,  washed  with  two  litres  of  boiling  water,  dried 
at  95°  to  98°  C.  and  then  weighed.  The  weight  of  these 
insoluble  fatty  acids  should  not  be  over  90  per  cent,  of  the 
weight  of  the  butter-fat. 


358    A  MANUAL  OF  HYGIENE  AND  SANITATION. 

Flour  and  Bread.  Wheat  Flour.  Characteristics: 
Almost  perfectly  white,  smooth,  and  free  from  grit;  no 
mouldy  or  unpleasant  odor ;  cohesive  when  lightly  com- 
pressed; no  signs  of  parasites  under  the  microscope;  water 
less  than  18  per  cent. ;  ash  less  than  2  per  cent,  or  more. 

To  determine  the  percentage  of  water  and  ash:  In  a 
weighed  platinum  (or  porcelain)  dish  place  about  50 
grammes  of  flour,  weigh,  and  dry  over  a  water-bath  for 
an  hour  or  so;  then  complete  the  evaporation  in  a  water- 
oven  until  there  is  no  further  loss  of  weight;  weigh,  sub- 
tract this  weight,  less  the  weight  of  the  dish,  from  the 
original  weight  of  the  flour.  Multiply  the  remainder  by 
100  and  divide  by  the  original  weight  of  the  flour.  The 
result  is  the  percentage  of  water.  Then  ignite  the  dried 
flour  in  the  dish  and  incinerate  till  there  are  no  longer 
any  black  particles  and  only  the  ash  remains;  cool,  weigh, 
subtract  weight  of  dish,  multiply  the  remainder  by  100, 
and  divide  by  the  original  weight  of  the  flour.  The  result 
is  the  percentage  of  ash. 

To  determine  the  percentage  of  gluten :  By  means  of  a 
glass  rod,  mix  a  weighed  quantity  of  flour  with  a  little 
distilled  water  into  a  stiff  dough;  then  repeatedly  wash 
away  the  starch  and  soluble  constituents,  kneading  the 
dough  with  the  rod  or  fingers,  and  continuing  until  the 
wash- water  comes  away  clear ;  the  gluten  and  a  small 
amount  of  fat  and  salt  remain.  Spread  out  on  a  weighed 
dish  or  crucible  lid,  dry  in  a  water-oven,  and  weigh;  mul- 
tiply by  100  and  divide  by  the  original  weight  of  the  flour. 
The  result  is  the  approximate  percentage  of  gluten.  The 
gluten  should  pull  out  into  long  threads;  otherwise,  it  is 
poor. 

An  excess  of  water  impairs  the  keeping  quality  and 
lessens  the  amount  of  nutriment  in  the  flour.  An  excess 


EXAMINATION  OF  AIR,   WATER,  AND  FOOD.    359 

of  ash  indicates  the  addition  of  mineral  substances.  A 
deficiency  of  gluten  indicates  that  the  flour  is  not  pure 
wheat  flour.  Parasites  and  fungi  especially  affect  or  live 
in  old  or  damp  or  inferior  flour. 

To  test  for  mineral  substances :  Shake  a  little  flour  in  a 
test-tube  with  some  chloroform,  and  allow  it  to  stand  for 
a  few  moments.  The  flour  floats  and  any  mineral  matter 
sinks  to  the  bottom,  when  it  can  be  removed  with  a  pipette 
and  examined  under  a  microscope. 

Wheat  Bread.  Characteristics  :  Fairly  dry,  light,  and 
spongy;  clean  and  nearly  white;  of  pleasant  taste;  not 
sodden,  acid,  or  musty;  ash,  not  over  3  per  cent. ;  no  para- 
sites or  mouldiness;  no  flour  other  than  wheat;  but  little, 
if  any,  alum;  no  copper  sulphate. 

Test  for  alum:  Add  5  c.c.  of  a  5  per  cent,  tincture  of 
logwood  and  5  c.c.  of  a  15  per  cent,  solution  of  ammo- 
nium carbonate  to  25  c.c.  of  water;  soak  a  crumb  of  the 
bread  in  this  for  a  few  minutes ;  drain  and  gently  dry. 
Alum  is  indicated  by  a  violet  or  lavender  color;  its  absence 
by  a  dirty-brown  color  on  drying. 

Test  for  copper  sulphate :  Draw  a  glass  rod  dipped  in  a 
solution  of  potassium  ferrocyanide  across  a  cut  slice  of  the 
bread;  copper  is  indicated  by  a  streak  of  brownish-red 
color. 

Test  for  ergot  in  flour  or  bread :  Add  liquor  potassae;  a 
distinct  herring-like  odor  (due  to  propylamine)  is  appreci- 
able if  ergot  be  present. 

An  excess  of  water,  an  unnatural  whiteness,  and  a  low 
percentage  of  ash  in  bread  indicate  the  addition  of  rice. 
Potatoes  give  an  increased  percentage  of  water  and  an 
alkaline  ash.1 

1  For  further  details  see  Fox's  "  Examination  of  Food,  Air,  and  Water,"  and 
Kenwood's  "Hygienic  Laboratory." 


INDEX. 


ACCESSORY  foods,  200 
Air,  59 

bacteria  in,  64 

currents,  102 

diseases  due  to  impurities  in, 
78 

examination  of,  339 

filtration  of,  95 

-propeller,  107 

-supply,  source  of,  95 
Alcohol,  223 
Alum,  test  for,  359 

use  of,  in  water,  153 
Ammonia,  "albuminoid,"  177,  351 

"free,"  177,  351 

test  for,  350 

Amylopsin,  action  of,  189 
Anderson's  process,  154 
Anemometer,  100 
Annatto,  test  for,  355 
Antiseptics,  267 
Antitoxin  theory,  53 
Antitoxins,  53 

method  of  preparing,  55 

statistics  of  use  of,  58 
Aqueous  vapors,  62,  69 
Argon,  61 
Artesian  wells,  139 
Artificial  ventilation,  95,  105 
Ashes,  298 
Aspiration,  97 
Atavism,  233 
Atmosphere,  59 

composition  of,  59 

impurities  in,  63 

weight  of,  59 
Atmospheric  contamination,  extent 

of,  90 
index  of,  90 


BACILLI,  37 
Backus  heater,  113 


Bacteria,  classification  of,  63 

definition  of,  32 

differentiation  of,  42 

discovery  of,  33 

in  air,  64 

parasitic,  45 

pathogenic,  46 

saprophytic,  44 

separation  of,  38 
Bacteriology,  32 
Bacterium  coli  communis,  175 
Bathing,  241 

rules  for,  242 

sea-,  242 

time  of,  242 
Baths,  cold,  241 

Russian,  244 

Turkish,  244 

warm,  243 

Beans,  nutritive  value  of,  217 
Bedding,  disinfection  of,  281 
Beef,  208 

-tea,  221 

recipe  for,  214 
Berkfeldt  filter,  the,  168 
Beverages,  226 
Bichloride  of  mercury,  273 
Bile,  action  of  the,  190 
Boric  acid,  test  for,  355 
Bread,  215 

wheat,  359 
Broths,  213 
Butter,  207 

examination  of,  356 
Buttermilk,  204 


CALCIUM  hydrate,  274 
Camps  of  detention,  296 

of  probation,  296 

of  refuge,  296 

Carbohydrates,  functions  of,  194, 
195 


362 


INDEX. 


Carbohydrates,  sources  of,  194 
Carbolic  acid,  273 
Carbon  monoxide,  poisoning  by,  84 
Carbonic  acid,  61 

effect  of,  66 
excretion  of,  67,  237 
poisoning  by,  84 
tests  for,  341 

Carpets,  etc.,  disinfection  of,  281 
Census,  the,  331 
Cereals,  the,  214 
Cesspools,  dangers  of,  300 
Characteristics,  transmission  of,  232 
Cheese,  206 

Chemical  treatment  of  water,  152 
Chloride  of  zinc,  274 
Chlorides  in  water,  176 

test  for,  345 
Chlorinated  lime,  272 

soda,  272 
Chlorine,  274 

fumigation  with,  281 

test  for,  345 
Cisterns,  131 
Clark's  process,  152 
Closets,  hopper,  315 

pan,  313 

plunger,  314 

siphon,  315 

valve,  313 

wash  out,  315 
Clothing,  245 

absorption  of  heat  by,  249 

advantages  of  woollen,  246 

conveyance  of  infection  by,  249 

materials  for,  245 

purpose  of,  245 

sophistication  of,  248 

tests  of  materials  for,  248 
Coal  gas,  composition  of,  85 

poisoning  by,  85 
Coffee,  221 

Cold  baths,  effect  of,  241 
Combustion  products,  71 

influence  on  health  of,  83 
Comparative  mortality  figure,  336 
Convected  heat,  109 
Cooking,  object  of,  190,  211 

thoroughness  of,  211 
Copper  sulphate,  273 
test  for,  359 

test  for,  349 


Corrosive  sublimate,  273 
Cotton,  247 
Cowls,  97 

Cramps,"  cause  of,  242 
Cubic  space,  94 
Culture  media,  41 


DEATH-RATES,  334 

daily,  335 

of  cities,  22 

standard,  336 

zymotic,  335 
Deep  wells,  138 
Deodorants,  267 
Detention  at  port  of  entry,  286 

camps  of,  296 

period  of,  in  quarantine,  287, 

293,  294 

Devices  for  ventilation,  101 
Dietetics,  183 
Diffusion,  95 

rate  of,  96 
Digestion,  physiology  of,  184 

the  gastric,  188 

the  intestinal,  189 

the  salivary,  187 
Digestive  ferments,  184 
Direct-indirect  radiation,  122 

radiation,  122 
Disease  defined,  27 

methods  of  study  of,  327 
Diseases  affecting  animals  used  for 
food,  210 

classification  of,  28 

due  to  impure  air,  78 

due  to  impure  drinking-water, 
142 

due  to  respiratory  vitiation,  82 

hereditary,  233 

transmissible  by  milk,  204 
Disinfectants,  chemical,  269 

comparative  table  of,  279 

thermal,  269 

Disinfecting  chamber,  steam,  271 
Disinfection,  29,  266 

evidence  of,  268 

of  infectious  cases,  279 

of  rooms,  280 

of  water-closets,  319 

thoroughness  of,  268 
Disinfector,  duties  of,  266 


INDEX. 


363 


Domestic  purification  of  water,  146 
Drinking-water,  infection  by,  145 
Duration  of  life,  mean,  337 
probable,  337 
Duty  of  physicians,  24 


EARTH-CLOSETS,  301 
Economy  in  heating,  109 
Eggs,  207 
Enzymes,  184 
action  of,  186 
characteristics  of,  185 
classes  of,  186 
Ergot,  test  for,  359 
Estimation  of  radiating  surface,  1 25 
Examination  of  air,  339 
of  butter,  356 
of  flour,  358 
of  food,  352 
of  milk,  352 
of  water,  344 
Exercise,  235 

amount  necessary,  240 

effect  upon  brain  development, 

239 

upon  digestive  organs,  239 
upon  heart  action,  238 
upon  heat  production,  238 
upon  respiration,  236 
Exhaust  system,  124 
Expectation  of  life,  337 
Extent  of  atmospheric  contamina- 
tion, 90 
External  ventilation,  88 


FACTORS  of  ventilation,  90 

Fans,  7 

Farr,  Dr.  Wm.,  20 

Fatigue,  cause  of,  240 

Fats,  constructive  property  of,  197 

digestibility  of,  195,  198 

functions  of,  195,  196 

melting  point  of,  357 

properties  of,  356 

sources  of,  195 

todetermine    specific  gravity 

of,  357 
Filters,  action  of,  156 

cleaning  of,  163 

construction  of,  158 


Filters,  material  for,  169 
Filtration,  155 

of  air,  95 

rate  of,  163 

regulation  of,  158 
Fire,  disinfection  by,  269 
Fish,  209 
Fixtures,  location  of  house-,  306 

trapping  of,  306 
Floor-space,  94 
Flour,  examination  of,  358 

test  for  minerals  in,  359 
Flush-tanks,  322 
Food,  180 

amount  necessary,  191 

classification  of,  181 

cooking  of,  190 

definition  of,  180 

examination  of,  352 

function  of,  180,  181 
Formaldehyde,  275 

methods  of  using,  276 

production  from  methyl  alco- 
hol, 278 

regenerator  for  vaporizing  so- 
lutions of,  277 

solutions  of,  276 
Formalin,  276 
Formic  aldehyde,  275 
Formula  for  ventilating  problems, 

93 

Free  pratique,  294 
Fresh-air  supply,  91 
Fruits,  218 
Frying,  213 
Fumigation,  281 
Furnaces,  hot-air,  117 
Furs,  247 


GARBAGE,  disposal  of,  298 
Gas  stoves,  112 
Gaseous  impurities,  65 
Gastric  digestion,  188 
Germ  theory,  33,  46 

arguments  for,  47 
Germicides,  266 
Gluten,    to  determine   percentage 

of,  358 

Glycogen,  194 
Grate  fires,  110 
Ground-water,  135 


364 


INDEX. 


Ground- water,  current  of,  136 
purification  of,  135 


HARD  water,  132 

diseases  due  to,  143 
Hardness  of  water,  178 
permanent,  132 
temporary,  132 
test  for,  348 
Health  denned,  27 
Heat,  air  movement  due  to,  98 
convected,  109 
disinfection  by  dry,  271 
radiant,  108 
transmission  of,  121 
Heredity,  230 
Hippocrates,  19 
Hospitals,  purity  of  air  in,  92 
Hot  air  flues,  119 

size  of,  119 
furnaces,  117 

air  supply  of,   119 
limitations  of,  120 
location  of,  118 
requirements  of,  117 
Hot-water  heating,  121 
House  drainage,  303 
-drain,  304 

construction  of,  305 
niters,  164 

classification  of,  165 
requisites  of,  165 
warming,  108 
Humoral  theory,  52 
Hydrogen  dioxide,  274 
peroxide,  274 
sulphide,  86 

symptoms  due  to  inhaling, 

86 

Hygiene  denned,  17 
personal,  228 
reasons  for  study  of,  24 
school,  253 
scope  of,  17-19 


ILLUMINATING  gas,  composition  of, 

85 

poisoning  by,  85 
Immunity,  theories  of,  52 
Impure  air,  diseases  caused  by,  78 


Impure  water,  effects  of,  142,  148 
Impurities  due  to  combustion,  71 

due  to  respiration,  67 

gaseous,  67 

in  air,  63 

mortality  due  to,  80 
Index  of  atmospheric  contamina- 
tion, 90 

Indirect  radiation,  122 
Infection  by  drinking-water,  145 
Influence  of  lighting  agents,  73 
Inland  quarantine,  295 
Inlets,  location  of,  103 
Internal  ventilation,  89 
Intestinal  digestion,  189 
Involution  forms  of  bacteria,  35 
Iron,  test  for,  349 
Irrigation,  325 


KEFIR,  204 

Koch's  postulates,  49 

Koumiss,  204 


LABARRAQUE'S  solution,  272 
Lake  water,  135 
Lead  in  water,  144 

test  for,  349 
Leather,  247 
Life-table,  factors  of,  338 
Light,  250 

germicidal  effect  of,  251 

influence  upon  health,  250 
upon  metabolism,  252 

penetration  of,  251 
Lighting  agents,  influence  of,  73 
Lime,  chloride  of,  272 

chlorinated,  272 

milk  of,  274 
Limit  of    permissible   respiratory 

impurity,  91 
Linen,  247 

Liquid  waste,  disposal  of,  302 
Location  of  inlets,  103 

of  outlets,  102 

Loomis-Manning  filter,   the,   170, 
171 


MARRIAGE,  proper  age  for,  231 
Mastication,  value  of,  190 


INDEX. 


365 


Mean  after-lifetime,  337 

age  at  death,  337 
Meat,  composition  of,  208 

diseased,  210 
Micrococci,  37 
Milk,  201 

as  a  carrier  of  disease,  204 

care  of,  202 

examination  of,  352 

of  lime,  274 

sterilized  cream,  203 
Mines,  atmosphere  of,  78 
Mortality,  cause  of  infant,  335 

due  to  impurities  in  air,  80 

rate  an  index  of  water-purity, 

149,  150 
of  infant,  335 

rates,  334 

Movement  of  heated  air,  98 
Mutton,  209 


NATURAL  ventilation,  95 
Nitrates,  178 

test  for,  346 
Nitrites,  178 

test  for,  347 
Nitrogen,  61 


OIL  stoves,  114 
Oleomargarine,  356 
Open  fireplaces,  110 
Ophthalmia  in  schools,  264 
Organic  excretion,  70 

matters  in  water,  178 
Outlets,    location    of  ventilation, 

102 

Overwork,  effects  of,  254 
Oxygen,  60 

absorption  of,  237 


PAIL-SYSTEM,  the,  301 
Paraform,  276 
Parasites,  45 
Pasteur  filter,  the,  168 
Pathogenic  bacteria,  46 
Pepsin,  action  of,  187 
Perflation,  97 

Permissible   respiratory  impurity, 
limit  of,  91 


Personal  hygiene,  228 
Petri  dish,  39 
Pettenkofer's  method,  343 
Phagocytosis,  theory  of,  52 
Phosphates,  test  for,  350 
Plenum  system,  124 
Plumbing  for  sewage,  303 
Pneumatic  system,  300 
Poisson's  formula,  329 
Population,  daily,  335 

estimation  of,  332 

increment  of,  331 

weekly,  335 
Pork,  209 

Portable  steam  radiator,  113 
Postulates  of  Koch,  49 
Predisposing  conditions,  29 
Products  of  combustion,  71 
Prophylaxis,  29 
Propulsion  system,  124 
Proteids,  functions  of,  193 

sources  of,  193 
Ptomaines,  45 
Ptyalin,  action  of,  186 
Pumping,  effect  of,  138 
Purification  of  air  by  fire,  89 

of  ground-water,  135 

of  river-water,  133 

of  water,  147 

by  subsidence,  151 
domestic,  164 
Purity  of  air  in  hospitals,  92 


QUARANTINE,  282 

conditions  requiring,  287 
inland,  295 
laws,  purpose  of,  283 
origin  of,  282 
original  meaning  of,  282 
railroad,  297 

regulations  at  port  of  depart- 
ure, 284 
of  entry,  287 
during  voyage,  286 
school,  262 
stations,  location  of,  289 

requisites  for,  290 
treatment  of  cargoes  in,  291, 

293 

of  passengers  in,  291,  293 
of  vessels  in,  290 


366 


INDEX. 


RADIANT  heat,  108 

Radiating  surface,   estimation  of, 

125 

Eadiation,  direct,  122 
-indirect,  122 
indirect,  122 
Kailroad  quarantine,  297 
Eain-water,  130 
cistern,  131 
Registers,  size  of,  120 
Removal  of  sewage,  298 
Respiration  impurities,  effects  of, 

67 
Respiratory  vitiation,  diseases  due 

to,  82 
River-water,  133 

purification  of,  133 
Roasting,  212 
Rubber,  247 


SALIVARY  digestion,  187 

Salts,  function  of,  in  digestion,  199 

sources  of,  199 
Sanitary  cordon,  295 

science,  17 
Sanitation,  17,  29 
Saprophytes,  44 
Schering^s  lamps,  278 

method  of  disinfection,  277 
Schizomycetes,  32 
Scholars,  headache  among,  256 

prevention  of  infection  of,  262 
School  furniture,  arrangement  of, 

258 

influence  of,  257 
-houses,  care  of,  261 
construction  of,  260 
location  of,  260 
ventilation  of,  260 
warming  of,  260 
water-supply  of,  261 
hygiene,  253 
infirmaries,  265 
pathology,  254 
quarantine,  262 
-rooms,  lighting  of,  259 
work,  duration  of,  254 
Sea-bathing,  242 
Sedimentation,  151 
Septicaemia,  50 
Sewage,  chemical  treatment  of,  324 


Sewage,  composition  of,  299 

disposal  of,  323 

intermittent  filtration  of,  324, 
325 

-plumbing,  303 

requirements  of,  303 

purification  of,  324 

removal  of,  298 

treatment  by  irrigation,  325 

by  sub-irrigation,  325 
Sewer-gas,  75 

bacteria  in,  75 

influence  on  health,  86 
Sewers,  319 

"  combined,"  319 

construction  of,  323 

"  separate,"  321 

shape  of,  319 

ventilation  of,  320,  322 
Shallow-wells,  136 
Shoddy,  248 
Sick-room,  care  of,  280 

disinfection  of,  286 
Silk,  246 

Smead  system,  103 
Soil,  the,  76 

-air,  75 

circulation  of,  77 
influence  on  health,  86 

-pipe,  the,  303 

location  and  construction 
of,  304 

-pipes,  testing  of,  310 
ventilation  of,  304 
Solids,  total,  in  water,  176 
Soups  and  broths,  213 
Source  of  air-supply,  95 
Special  diseases  due  to  impurities 

in  air,  87 
Spirilla,  37 
Spores,  35 
Statistical  inquiry,   principles  of, 

328 
Steam,  disinfection  by,  270 

-heating,  122 
Steapsin,  action  of,  189 
Sterilization,  39 

fractional,  40 
Sterilized  milk,  203 
Sterilizers,  40 
Stimulants,  cautions  in  use  of,  224 

classification  of,  220 


INDEX. 


367 


Stimulants,  function  of,  220 

indications  for  use  of,  224,  225 
Stoves,  111 

gas,  112 

objections  to,  112 

oil,  114 

Sub-irrigation,  325 
Subsidence,  151 
Subsoil-water,  135 
Sulphate  of  copper,  273 
Sulphur  dioxide,  275 

fumigation  with,  281 
Sulphuretted  hydrogen,  86 
Sulphurous  acid  gas,  86 
Surface-water,  132 


TEA,  221 

Theory  of  antitoxins,  53 

of  Biichner,  52 

of  Chauveau,  52 

of  Metschnikoff,  52 

of  Pasteur,  52 
Total  solids  in  water,  176 
Toxaemia,  50 
Toxins,  45 
Trap,  bell-,  309 

Bower's,  309 

Cudell's,  309 

inspection  of,  310 

McClellan's    an  ti- siphoning, 

309 
Traps,  307 

S,  or  siphon,   307 

seal  of,  308 

sink  or  pot,  308 

siphoning  of,  309 

vent-pipes  for,  309 
Trillat's  method  of  disinfection,  277 
Trypsin,  action  of,  189 
Typhoid  fever,  150 
Tyrotoxin,  204 


VACCINATION  of  scholars,  264 
Variety  of  food,  necessity  for,  183, 

200 

Vegetables,  the,  217 
Velocity  of  air-currents,  98 
Ventilating  grates,  111 

problems,  formula  for,  93 
Ventilation  and  heating,  88 


Ventilation,  artificial,  95,  105 
devices  for,  101 
external,  88 
factors  of,  90 
internal,  89 
natural,  95 
of  sewers,  320,  322 
of  water-closets,  318 
Ventilators,  97 
Vital  statistics,  327 

numerical    standard    of, 

328 
variation  in,  329 


WASTE  PIPES,  304 
Water,  126 

ammonia  in,  177 

bacteriological  analysis,  175 

bottle  for  collecting,  345 

-carriage  system,  302 

chemical  treatment  of,  152 

chlorine  in,  176 

classification  of,  141,  179 

-closets,  disinfection  of,  319 
location  of,  318 
requisites  for,  312 
ventilation  of,  318 

diseases  caused  by  impuritit 
in,  142 

double  supply  of,  128 

effects  of  impure,  149 

examination  of,  173,  344 

excretion  of,  237 

ground  or  subsoil,  135 

hardness  of,  132 

lead  in,  144 

meters,  129 

nitrates  in,  178 

nitrites  in,  178 

phosphates  in,  178 

-purity,  index  of,  149,  150 

quantity  of,  necessary,  126 

rain,  130 

river,  133 

sewage  pollution  of,  134 

sources  of,  1 29 

storage  of,  151 

supply  of  cities,  127 

surface,  132 

the  examination  of,  173 

the  purification  of,  147 


368 


INDEX. 


Water,  total  solids  in,  176 
Wells,  deep,  138 
shallow,  136 

Well-water,  pollution  of,  137,  140 
Welsbach  light,  the,  74 
/,  Wheat,  214 


Winds,  96    . 
Wool,  245 


ZINC  chloride,  274 
Zooglea,  37 


